Preheat oven to 350°F and line a large baking sheet with parchment paper
Whisk together eggs and brown sugar. Add in drippy peanut butter and vanilla extract, mix until smooth.
In a separate bowl, mix together flour, baking soda and baking powder. Add dry ingredients to wet and mix until dough-like.
Separate the batter evenly into two bowls (about 3/4 cup for each). Mix 1/3 cup mini chocolate chips into one batter and set aside. For the other batter, mix in the cacao powder and milk (of choice), then add in the remaining mini chocolate chips. If either batter isn't firm enough to roll into balls, refrigerate for 20-30 minutes.
Portion out 20 (about ½ heaping tbsp) balls for each batter. Then, gently roll together one cookie dough and one brownie batter to form the brookie dough. Continue until all are combined.
Bake for 9-11 minutes. Let cool & enjoy!