Gather all ingredients.

Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking dish.

Prepare cookie layer: Beat 1/2 cup butter, 1/2 cup brown sugar, 1/4 cup white sugar, and 1/2 teaspoon vanilla in a large bowl until creamy. Add one egg; beat until light and creamy, about 2 minutes.

Whisk 1 1/4 cups flour, 1/2 teaspoon salt, and baking soda in a bowl. Gradually stir flour mixture into butter mixture until dough is combined. Stir chocolate chips into dough. Spread dough evenly into the prepared baking dish; set aside.

Prepare brownie layer: Stir 1 cup sugar, 1/2 cup melted butter, and 1 teaspoon vanilla in a bowl; add two eggs and beat well. Mix in cocoa powder until well-combined. Stir in 1/2 cup flour, baking powder, and 1/8 teaspoon salt until batter is combined. Pour over cookie layer and spread to cover completely.

Bake in the preheated oven until a toothpick inserted into the center comes out clean, 20 to 25 minutes. Cool completely before cutting into 20 bars. Enjoy! A brookie is part brownie, part cookie, and totally delicious. Fudgey and chewy, this is sure to be your new go-to at-home dessert. Serve it warm with a scoop of vanilla ice cream for the ultimate bite.