Preheat oven to 350℉. Line a cookie sheet with parchment.
Melt your butter in a heat-safe mixing bowl. Note: It doesn’t need to be ALL the way. See photos for an example- I’ve found the best stage is when about half the butter is liquid, but the rest is super soft. soft. Like the texture of pudding. You want it to easily stir completely smooth when you touch it.
Mix in white and brown sugars, egg yolk and vanilla.
Measure your flour by lightly spooning it into your measuring cup and then leveling with a knife. Avoid scooping with your measuring cup. Sprinkle flour, cocoa powder, baking soda, and salt on top and then mix together. Stir in almost all the chocolate chips- I like to save about a tablespoon to place on top of the cookie before baking.
Form dough into one large ball and place on prepared baking sheet. Gently press down to about ¾ inch thick. If you saved a few chocolate chips, distribute them on the top of the cookie.
Don't overbake! Keep an eye on it and err on the side of under-baking since chocolate dough is easy to over bake! Bake for 12-14 minutes (I like to set my time for about 10 so I can really watch it close at the end), until edges are set and center looks set, but still soft.
If desired, sprinkle a little flaky sea salt over the cookie immediately upon removing from the oven.
Let cool for 10-15 minutes. Enjoy!
Notes
Because we are working with such small ingredients it's important that you measure them correctly. It's very easy to alter your dough for any of these giant cookies simply by not measuring your flour correctly, packing your brown sugar too much, or using a small egg. We've included details in the recipe to help with this!
These cookies usually get eaten right away at our house, but if you happen to have leftovers, simply store in an airtight container at room temperature. Homemade cookies are safe to eat for a week or more when stored this way, but they will definitely have the best taste and texture the first couple days.
This cookie is also the perfect size for a pizookie for sharing. Just press dough into a standard pie plate and bake as directed. Place a few scoops of vanilla ice cream on it while it’s still warm and dig in.