Chocolate Mousse Crunch Cake

CATEGORIES: Cakes and Cupcakes

This Chocolate Mousse Crunch Cake is my all-time favorite special occasion cake. Not only does it wow people presentation-wise, but it’s pretty knock-your-socks-off tasty as well. As long as you like chocolate. Because if you’re a chocolate hater, this recipe isn’t for you.  It’s got 2 layers of rich chocolate cake, sandwiched with decadent chocolate mousse, drizzled with ganache and sprinkled with chopped toffee bits.  If you like, you can even top it with a cloud of whipped cream like I did in these photos.

chocolate cake on cake stand

Make-Ahead Options

One of the great things about this easy chocolate cake recipe is that you can just use a boxed cake mix. I figure that there’s so much going on here that you don’t need to bother with a from-scratch chocolate cake, you know? And if you make the ganache ahead of time and just heat it up, and make the cake ahead of time, by a few hours or a day or even a few days (just wrap the layers in plastic wrap and freeze them), the rest comes together in no time.

chocolate cake on platter

You can bake the cake layers ahead of time if you like and store them in the freezer until ready to use.  Our favorite cake pans to use are the kind with straight sides like these ones. The filling for this cake is a rich chocolate mousse that’s incredibly easy to make.  It actually makes more mousse than you probably need, so feel free to fill it as thick or as thin as you like and snack on the rest- because you made the cake so you get the extra mousse!

cake with mousse filling

Fill and Top the Cake

This chocolate cake is topped with…you guessed it- more chocolate. To get nice drips down the sides, avoid trying to actually spoon ganache down the side of your cake.  Spread a nice even layer right on top.  Then use a spoon to gently start spreading toward the edges.  You just need to nudge a little and you’ll see the chocolate wave start moving toward the side and down the edge.  Let gravity do the work!  That way you get nice pretty drips without overdoing it.  You can sprinkle some toffee bits on top and you are ready to serve!

ganache dripping on cake

OR, if you like, I sometimes like to top it with a fluffy cloud of sweetened whipped cream as well.

chocolate cake with whipped cream on top

Helpful Tools for this Recipe

Straight-Sided 8″ Cake Pans

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chocolate mousse cake on cake stand

Chocolate Mousse Crunch Cake

  • Author: Kate Jones


An easy chocolate mousse and toffee filling is sandwiched between moist layers of chocolate cake and finished off with rich, gooey ganache and more toffee bits.


1 package Duncan Hines Devil’s Food Cake
1 recipe (give or take a little) Chocolate Ganache
Crushed Heath bars or a bag of chocolate-covered Heath bits
1 teaspoon unflavored gelatin
1 tablespoon cold water
2 tablespoons boiling water (just heat it in a small bowl in your microwave)
1/2 cup sugar
1/4 cup unsweetened cocoa powder
1 cup whipping cream
1 teaspoon vanilla
Optional: extra sweetened whipped cream for serving


Bake cake according to cake mix instructions in 2 8″ round pans. Allow to cool and set aside. This can be done several days in advance; just freeze the cakes when you’re done.
In a small bowl, combine gelatin and cold water and allow to stand for about 1 minute. While gelatin is softening, bring about 1 cup of water to a boil in the microwave and measure out 2 tablespoons. Discard the rest. Whisk the 2 tablespoons of boiling water into the softened gelatin and allow to cool slightly.
In a medium mixing bowl, combine sugar, cocoa powder, whipping cream, and vanilla. Beat with an electric mixer until medium-stiff peaks form. Mix in gelatin mixture and refrigerate for 30 minutes.
Prepare ganache (if you haven’t already) according to directions.
With a serrated knife, carefully slice the dome-iest part of each cake layer off so the layers are level. Place one layer on the serving plate and spread chocolate mousse over the cake (see note below). Sprinkle with Heath bits.

Place second layer on top of Heath bits.

Spoon ganache over the top layer, allowing it to drip down the sides.  Sprinkle with additional Heath bits and refrigerate until ready to serve. If desired, top with sweetened whipped cream before serving.


This recipe makes more mousse than you will probably need. Feel free to use as much or as little as you desire in the filling and snack on the rest!

Keywords: Chocolate Cake, Chocolate Mousse, Chocolate Crunch Cake, Occasion cake


  1. This cake looks heavenly! I think rich is an understatement!!! My anniversary is next week and my hubby LOVEs mousse, so this will make for a perfect dessert! Thanks for sharing, I really enjoy your blog and the yummy recipes!

  2. Looks fan-freakin-tastic!!

    Am I just missing something or do you only use half the mouse? What do you usually do with the extra? Just eat it cuz that'd be great or do you make something else?

  3. Happy birthday. This was so not the post a pregnant chick should open first thing in the morning! Drool on the computer could totally be bad. My bday is coming up in April and I am trying to figure out who I could print this out for and con/beg/plead/strong arm into making this for me!

  4. This looks wonderful. I am preheating my oven right now so I can make it. Just thought I'd point out an easy way to avoid the problems you might have by halving the mousse recipe -just boil a quarter cup of water and then measure out the 1 tablespoon that's needed.

  5. Looks divine!! I will have to make this soon. My husband will just love it! 😀 Thanks for the great posts, I look forward to reading them!

  6. Good thing I don't have a very good reason to make this anytime soon… this looks very dangerous!!(I am sure I will come up with a reason soon!)YUM!

  7. That looks SOOO good! Now I need to plan something so I'm not left with half a cake to myself at home all day long….you know? Thanks for the great recipes, looking forward to the next year of delicious food and great ideas!

  8. My job is dessert every Sunday when my extended family gets together. This looks wonderful and I will be making it this weekend! Thanks for all of your wonderful ideas.

  9. Looks delish, but like Amber I'm curious what do you do with the other half of the chocolate mousse? Or is it possible, dare I say, to make a half batch of the mousse?

  10. Wow! This looks AMAZING!! I have missed your blog so much. [We had laptop issues for months and have now upgraded to a brand-new one – wahoo!!] I am half-tempted to go back through ALL of the posts I missed and catch up.
    Time to wipe the drool of the new computer…. 😉

  11. That looks so good! Congrats on your blog. If I could change one thing…it would be for you to add an option so I could print recipes on 3 x 5 or 4 x 6 card sizes. Otherwise, I wouldn't change a thing!

  12. Just needed to say that I LOVE this blog! I think I might just try out this cake on a family get together with the in-laws. P.S…Your pizza dough recipe is awesome. I made it this week and it's the first time out of many previously failed attempts that I've made a pretty and yummy pizza.

  13. This is the most fantabulous thing I have seen in ages. You gals could rule the world and I would totally support you. Happy, happy birthday. I'm a new reader but fully dedicated and spreading the word.

  14. I tried this tonight and can't get it to work, can't figure out why, it won't stiffen up, more like a slightly runny pudding, then I beat it more and gets runnier. any ideas??

  15. Just wanted to let you know that I am a new AVID follower of your blog. I have loved every single recipe I have tried (which is a lot), but this was the cherry on top. My husband said he had never had a cake this good. 🙂 AMAZING! And the self-regulating thing? Totally false for us. We both had two BIG slices. 🙂 Apparently we have a high choco-tolerance.

  16. Bethany–I'm wondering if something was up with your whipping cream because I've never had whipping cream not whip up for me. Or maybe you accidentally grabbed half and half (I've done that SO many times! They need to keep them at opposite ends of the dairy case! 🙂 )?

  17. No it's whipping cream, I considered getting the "Heavy" whipping cream but decided on the regular like the recipe said. :o(
    I will try it again this week with different whipping cream, do you think Heavy would work too.

  18. Looks fabulous and I love to bake! Hubby does all the cooking and I'm in charge of the sweet stuff! I may have to make this very soon!! Yum!!

  19. I think this looks awesome, but when I made the mousse, the gelatin just clumped up in it instead of mixing in. What did I do??? I have to take it to dinner and don't have time to make it again, so I think I'll mix in some of the toffee with the mousse and hopefully no one will notice the gelatin?

  20. Yay! I got it to work! Same whipping cream, so not sure what the problem was, but maybe it was my Bosch mixer? with the center post and the small amount of mousse I think it had a problem mixing it well at all, I tried a hand mixer last night too but it was probably to late. This morning I did it with a hand blender and it worked great! And so yummy! I am so excited, using it in the filling for my son's Monster b-day cake today and adding gummy worms to the mousse for the kids!

  21. Rachel, I had that problem last night, I left it too long and it was a rubber disk, but this morning I I mix it a bit with the cold water, only let it stand one minute, then mixed in the hot water, and maybe let it cool one minute or so, then added it to the already whipped cream and mixed again. worked better to do it at the end otherwise it cools to much.

  22. Love everything you make. L. O. V. E. Would this cake do well sitting as a centerpiece during a dinner? Would I want to freeze partially, or just refridgerate in prep for that?

  23. This cake looks too mouth-watering delicious to be true! Have you ever tried cutting the cake layers in half to make a torte? It would use more of the mousse and ganache with the two extra layers. Might make the whole thing teeter and fall over, though.

    I love your blog and have tried MANY of your recipes. Happy birthday! (and I totally agree with the woman who thinks you should send a slice of this cake to everyone who leaves you a comment!)

  24. This looks like the closest thing to Gregg's Heath Bar Crunch Cake but has mousse in it.. OMG IM IN LOVE!!!!!!!!!

    Happy belated birthday blog.

  25. Are Duncan Hines cake mixes your favorite? Or would any Devil's food cake mix work just fine? I have Betty Crocker, but haven't tried Duncan hines! This looks so good!

  26. I made this cake for Easter Dinner desert and it was fabulous! I can't wait to make it again. Thanks for the awesome recipe.

  27. Crystal Burch, this was the cake I was going to make you on Friday! Which I clearly did NOT because you got a birthday cookie instead and that didn't even have a candle in it. I owe you big time…

  28. I made this for Memorial Day. It was delicious, but the mousse never got fluffy it was more like an icing so I'm not sure what I did wrong.

    Oh well, that gives me an excuse to make it again!

  29. Hi! I love your relaxed approach to making recipes fun.
    Do you ever "docter" a chocolate cake mix as you did with the yellow in the Caramel Cake?

  30. Mclemoma–I've tried doing the standard substitutions like we have in the white cake mix and my cake came out really dry, so I'm working on finding something that works! Stay tuned–hopefully we'll have something soon! 🙂

  31. If I am wanting to make just the mousse part of this cake to use as a dessert crepe filling, how far do you think I can make it in advance without the texture getting too runny?

    P.S. Still my favorite cake. 🙂

  32. Laura, I wish I had a better answer for you, but I honestly don't know! 🙂 I *imagine* as long as you keep it in an airtight container, you could make it up to a couple of days ahead of time because I've had the cake as well as the cream puffs for a few days and it's been fine. But I can't say for sure. I'm sorry!!

  33. This cake is SO good. I just made it for my mother in laws birthday. I saved the tops of the cake that I cut off and topped it with the leftover mousse, and some ganache. Yummy way to eat all of the extra's!

  34. hey kate! Question for ya!

    i finally am getting a chance to make this amazing cake! YAY – it's for a friends b-day and we're going to a resteraunt, so it will be sitting for a little while do you think it would do ok sitting out if it had been in the fridge all day before we head out to dinner?
    (also, can i make it a full day ahead? and keep it in the fridge? it should be fine right??)

    Please let me know what you think! thanks!! 🙂
    thanks! sara

  35. Hey, Sara! I'm so sorry it's taken me a few days to get back to you–I've been super sick. I hope I'm not too late here! Anyway, yeah, the cake should be fine if it's been sitting in the fridge all day; in fact, it will probably be easier to transport that day. Ditto on making it a day ahead of time–the ganache won't be super shiny, and just make sure you don't have any weird rogue flavors in yoru fridge and you'll be totally fine.

    Hope that helps! 🙂

  36. Sorry you've been sick Kate! Hope you're feeling better!!

    Thanks so much for getting back to me – you're not too late! I am planning to bake the cakes tonight and put everything together tomorrow for our outing on friday!:)
    Sounds like it will work perfectly – thanks again for your help!!! :O)

  37. After much searching for a perfect dessert to serve company, I settled on this one. Easy and absolutely DIVINE! I did add lots more chocolate ganache because it soaks it up–it was swimming in the stuff. Delicious!!

  38. FANTASTIC cake! Wishing I would have made two for book club last night so that I could have leftovers for breakfast this morning :).

    To simplify the mousse step this time I made a small box of chocolate pudding with 1 1/2 C. milk and let that set for about five minutes in the fridge. I then whipped 1 C. whipping cream (sweetened with a touch of powdered sugar) and carefully folded in about half of my prepared pudding. Just as yummy as the original and less work.

  39. Here's a question…I was thinking about pouring some evaporated milk on the cake after taking it from the oven to make it moist, but not so much that it would be soggy like a tres leches cake. What are you thoughts about that? Do you think it would be good?

  40. Why couldn’t you just half each cake layer so that you have four thinner layers of cake then you could use all of the mousse by putting some between each layer? I’ve made a different mousse cake than this one before, and it had at least 3 or 4 layers.

  41. I’ve made this cake twice now and it got rave reviews. I make the chocolate cake in three layers, which allows me to use all the mousse and makes a stunning presentation. A tip – Spread the mousse on two of the cake layers, then refrigerate before putting them together to help the mousse set up firm. It also helps to refrigerate the ganache just a little to get the right consistency before pouring on the cake. Sometimes if you pour it right after you have melted the chips it can be a little too runny. Thanks so much for the recipe!!

  42. I have been looking for a reason to make this cake.. I mean.. Me and my 3 yr old are the only ones in our house who would eat it. (hubby not a sweet loving guy). I thought.. maybe I will throw a party.. just so I can make it. But I don’t really have time. So, last night as I was laying in bed I decided I’m going to turn it into cupcakes. Will put the ganache on first and the use the mousse as kind of a frosting. Do you think that would work? I have never made mousse before. Then I can keep several for us, and give the rest to the neighbors hehe.

  43. This looks and sounds absolutely divine!
    If you want just 1 tbsp boiling water, just fill your spoon from a boiling kettle!

  44. I haven’t made this cake, but I made just the mousse this weekend, I doubled the recipe and it was the perfect amount to fill a sheet cake, just FYI!

  45. Oh, and the doctored up cake mix recipe (the “easy white cake” you have on here) I have made into yellow cake and chocolate cake it it worked BEAUTIFULLY every single time. I even doubled it for yellow cake and then doubled it for chocolate cake then marbled half the yellow and half the chocolate in 2 sheet cake pans then (see previous comment) made the mousse and make the “perfect cupcake frosting and filling” x4 and frosted the whole cake with that. It was a HUGE sheet cake, probably would feed 60 people. And I got lots of “BEST birthday cake I’ve ever had!”. So… there you go.

  46. I made this cake last night…FABULOUS. My friends were blown away, I hated to tell them that it really was easy. Your cookbook is awesome! Thanks for getting your recipes published in book form!

  47. Hi, I can’t wait to get started!!!!
    I was wondering if this would work well with you Old-Fashioned Chocolate Cake serving as a substitute for the boxed cake mix?
    and… we don’t have Heath bits where I’m from… what may I use as a substitute please?

    1. Steph, yes that old fashioned cake would be fantastic! For the Heath bits, you could use any sort of toffee or similar candy. Where are you from? There are lots of candy bars that would be good crumbed up in there too- just pick one you like!

  48. Ta! (& many thanks for sharing all those delicious recipes!)
    You’ve made me want to bake again 🙂

  49. I’m on my second try tonight with the mousse. It’s coming out grainy and runny. I’m using the heavy whipped cream, so it can’t be that. Any suggestions? I really want this to work!

  50. I made this for a silent auction tonight and people were hovering around it waiting to outbid anyone that stepped near it!

  51. I’m wanting to cover the whole cake with the mousse first then drizzle the ganarche over it. Do you think that will work or will the ganarche make the mousse run down the sides too and become a gross looking mess?

  52. This was really yummy, and the ganache is so good I have no words~
    My question is why every time I attempt to make mouse I get the gelatin chunks 🙁 how do you avoid this?
    thank you in advance!

    1. You’ve got to whisk really well, if you have lumps, warm the gelatin in the microwave until they’re all dissolved.

  53. Totally made this for my 3-year-old’s birthday yesterday (yes, I know, she doesn’t care, but I didn’t want another plain ol’ box cake with box frosting and I had the ingredients for this one. Holy cow!! Fabulous!! LOVED the mousse (dang, how did I not know it was that easy to make mousse?? unfortunately, it is now dangerous for my weight that I know this). The ganache I struggled with and we actually ate the cake before it was chilled, so when I had a piece later, the ganache tasted much better to me. Anyway, FABULOUS cake!! So love it!! Now can’t wait to try the white chocolate peppermint version!!

  54. Can you please help me fine the Chocolate Mousse recipe? I though I had done it before but I can’t fine it now. Thanks!

  55. The ganache link isn’t working! We love this recipe and I need to make it for a baby shower this week. Can you please help me find it?
    I’m at work

  56. Your recipe of 1/2 c. choc chips and 1/2 c. heavy cream for ganache as part of the chocolate mousse crunch cake recipe turned out very thin, just like chocolate milk. Is there a missing ingredient that would thicken it a bit?

    1. It’s very thin while still warm, but thickens considerably as it cools. If you’d like it even thicker, just decrease the amount of cream a little.

  57. This is my favorite cake! I’m a sucker for chocolate cake but, the mousse makes it even better. Sometimes, I omit the toffee chips and do fresh raspberries!

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