Prepare the Pan: Press a large piece of parchment paper into an 8×8 baking pan, creasing the bottom edges. Chill it in the freezer for about 10 minutes until firm.

Preheat and Line: Line the baking pan with parchment paper so it hangs over the sides, then preheat your oven to 350°F (180°C) for optimal baking conditions.

Whisk the Mixture: In a mixing bowl, whisk together the granulated sugar, brown sugar, eggs, and vanilla extract until smooth and well combined.

Melt the Ingredients: Melt the butter and chocolate chips together in a saucepan over medium heat until smooth. Stir in the cocoa powder and combine this mixture with the egg mixture until fully blended.

Combine Dry Ingredients: Gently fold in the all-purpose flour, espresso powder, and fine sea salt to the chocolate mixture until just combined.

Layer the Batter: Pour half of the brownie batter into the prepared pan, spreading it evenly to the edges. Place the frozen cookie butter square in the center and cover with the remaining batter.

Add Toppings: Crumble the Biscoff cookies over the top and drizzle warm cookie butter generously.

Bake the Brownies: Bake for 30-40 minutes. They are ready when a toothpick inserted comes out with a few moist crumbs.

Cool and Serve: Allow the brownies to cool completely on a wire rack to set. Drizzle more cookie butter over the top before cutting.