This combination of brownie and peanut butter cookie is a definite must try, because a warm peanut butter brookie with a glass of fresh milk is absolutely heavenly!
Mix the brownie batter according to package instructions and pour into a greased or parchment lined 13 by 9 inch baking dish (*see note below).
Cream the butter and sugars well for the peanut butter cookie dough, then stir in beaten egg, milk and peanut butter until smooth and creamy. Add salt, baking soda and flour, then mix until flour is well incorporated. Gently fold in chocolate chips/bits.
Dollop the peanut butter cookie dough over the brownie batter, then cover the baking dish with aluminum foil. Bake covered for 20 minutes (to prevent the cookie dough from baking faster than the brownies), then remove the foil and bake for another 25-30 minutes until the center of the brookies is almost completely set (the brookies will continue baking a bit as they cool).
Allow to cool completely before cutting, then serve and enjoy! See more notes and photos below.
Notes
You can also use 1/2 of your favorite chocolate bar, broken into small bits, or you can do a combination of chocolate chips and candy bar bits. More notes on this recipe below!