01 - Preheat oven to 350°F. Line a 9x9 inch square baking pan with parchment paper, leaving a slight overhang on the sides for easy removal.
02 - In a medium bowl, whisk melted butter and sugar until combined. Add eggs and vanilla, beating until glossy. Stir in cocoa powder, flour, and salt until just incorporated. Spread evenly across the bottom of the prepared pan.
03 - In a separate bowl, cream softened butter with both sugars until light and fluffy. Beat in egg and vanilla. Add flour, baking soda, and salt, mixing until just combined. Fold in chocolate chips.
04 - Dollop spoonfuls of cookie dough over the brownie batter. Gently flatten and spread to mostly cover the brownie layer—it's fine if some brownie peeks through.
05 - Bake for 30–35 minutes until edges are golden and the center is just set. Do not overbake—brookies should remain fudgy inside.
06 - Allow to cool completely in the pan before lifting out using the parchment overhang. Cut into 16 squares and serve.