1Add 1/2 cup of brown butter, 1/4 cup of white sugar and 1/3 cup of brown sugar to a bowl.
2Whisk until it goes from a grainy mixture to a creamy, smooth texture.
3Add one room temperature egg and 1 1/2 teaspoons of vanilla extract. Mix well.
4Add the dry ingredients: 1 cup of flour, 1/4 teaspoon of baking powder, 1/4 teaspoon of baking soda and a pinch of salt.
5Mix until combined.
6Add 1 cup of chocolate chips and mix.
7Place the cookie dough in the fridge until the brownie side is done.
8Melt 4 ounces of dark and semi-sweet chocolate with 3 tablespoons of butter. Melt this with 3 tablespoons of butter using a microwave (short bursts) or double boiler.
9Let the chocolate and butter mixture cool.
10Add 1/4 cup of white sugar, 2 tablespoons of brown sugar, and 1 large egg to the mixer bowl.
11Whip the mixture with a mixer until it becomes much lighter in color.
12Add 1/2 teaspoon of vanilla extract and the cooled melted chocolate and butter mixture.
13Mix until well combined.
14Fold in the dry ingredients: 2 tablespoons of cocoa powder, 1/4 cup of regular flour, a pinch of salt and a 1/2 teaspoon of baking powder. Mix until combined.
15Place the cookie dough and brownie batter in half-sized balls on a baking sheet lined with parchment paper.
16Combine half a cookie dough ball with half a brownie batter ball to create a "brookie" dough ball.
17Bake the cookies at 3500F (1750C) for 10-12 minutes.