Two beloved desserts come together in one perfect bar cookie.
if you look on the back of the box, some brownies have instructions for a 9x13 pan, and some say the largest pan option is 8x8 or 9x9. Try to find one that is made for a smaller pan (the 8x8 or 9x9). You will bake them in a 9x13, thus creating a thinner brownie layer that can complete cooking in the same time as the cookie layer. If you get the larger box, your brownies might be too thick and be undercooked. If all you can find is the larger kind, then maybe make 2 or use half the batter in an extra small pan for a snack :)