reheat Your Oven: Start by preheating your oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper for easy removal.
Mix the Dry Ingredients: In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt. Set aside.
Cream Butter and Sugar: In a separate large bowl, cream the softened butter and granulated sugar until light and fluffy.
Add Egg and Vanilla: Beat in the egg and vanilla extract until well combined.
Combine Mixtures: Gradually stir the dry ingredients into the wet mixture until just combined. The batter may be thick!
Fold in Chocolate Chips: Gently fold in the chocolate chips until evenly distributed throughout the batter.
Spread the Batter: Spoon half of the brownie batter into the prepared baking pan, smoothing it into an even layer.
Layer the Cookie Dough: Take your cookie dough (you could also use store-bought dough) and drop spoonfuls over the brownie base. Use the back of a spoon or your fingers to gently spread it out as best as you can.
Swirl: Finally, take the remaining brownie batter and dollop it on top of the cookie layer. Use a knife to swirl through both layers for a marbled effect.
Bake: Bake in your preheated oven for 25-30 minutes or until a toothpick inserted in the center comes out with a few moist crumbs.
Cool and Cut: Allow to cool in the pan for at least 15 minutes before lifting out using the parchment paper and cutting into squares.
