Preheat your oven to 350°F (175°C). Grease a 9x9 inch baking pan and line it with parchment paper, leaving some overhang on the sides for easy removal.

In a medium bowl, whisk together the melted butter and granulated sugar until well combined. Add the eggs and vanilla extract, whisking until the mixture is smooth and slightly glossy.

In a separate small bowl, stir together the all purpose flour, cocoa powder, baking powder, and salt. Add these dry ingredients to the wet ingredients and mix with a spatula just until you no longer see streaks of flour. Gently fold in the 1/2 cup of chocolate chips.

Pour the brownie batter into your prepared baking pan and use the spatula to spread it into an even layer. Set this aside while you make the cookie dough.

In a separate large bowl, using an electric mixer or a stand mixer with the paddle attachment, cream together the softened butter, brown sugar, and granulated sugar until the mixture is light and fluffy. This usually takes about 2 minutes. Beat in the egg and vanilla extract until everything is well combined.

In another small bowl, whisk together the 1 1/4 cups of all purpose flour, baking soda, and salt. With the mixer on low speed, gradually add the dry ingredients to the wet ingredients, mixing just until combined. Stir in the 1 cup of chocolate chips with a spatula.

Take spoonfuls of the cookie dough and drop them evenly over the brownie batter in the pan. You don't need to spread it perfectly; it will spread as it bakes.

Place the pan in the preheated oven and bake for 30 to 35 minutes, or until a wooden skewer or toothpick inserted into the center comes out with moist crumbs attached, but not wet batter. The edges should be set and the top golden brown.

Remove the pan from the oven and let the brookies cool completely in the pan before cutting. This ensures the brownie layer sets up properly and gives you clean, neat slices. Use the parchment paper handles to lift them out of the pan and cut into squares.