Preheat oven to 350 F
Line an 8×8 square baking dish with parchment paper
Prepare the brownie layer first by mixing all the dry ingredients together in one bowl, and all the wet ingredients in another bowl
Add the wet ingredients into the dry, whisking together until fully incorporated and there are no clumps
Transfer the batter to the bottom of the baking dish, and use a spatula to smooth, if needed
Prepare the chocolate cookie later: Mix all the dry ingredients except chocolate chips in one bowl, and all the wet ingredients in another bowl
Add the wet ingredients into the dry, whisking together until fully incorporated and there are no clumps
Fold in half of the chocolate chips and stir until combined
Use a spoon to drop dollops of cookie dough on top of the brownie layer, using a spatula to smooth, if needed. Top with the other half of the chocolate chips
Bake for about 25 minutes, or until a toothpick comes out clean