01 -
Preheat oven to 350°F. Grease a 9×13-inch baking pan or line with parchment paper for easy removal.
02 -
In a large mixing bowl, whisk melted butter, granulated sugar, and brown sugar until smooth. Add eggs one at a time, mixing well after each addition. Stir in vanilla extract until fully incorporated.
03 -
In a separate bowl, sift together flour, cocoa powder, baking powder, and salt. Gradually stir the dry mixture into the wet ingredients until just combined, avoiding overmixing.
04 -
Scoop out approximately 3/4 cup of brownie batter and set aside. Pour the remaining batter into the prepared pan. Spoon dollops of Biscoff cookie butter across the surface. Swirl with a knife or toothpick to create a marbled effect.
05 -
Dollop the reserved brownie batter over the swirled Biscoff layer and use a knife to further marble the surface, leaving visible streaks of Biscoff.
06 -
Bake for 25–30 minutes, or until a toothpick inserted into the center emerges with a few moist crumbs. Avoid overbaking to maintain fudgy texture.
07 -
Allow brownies to cool in the pan for at least 15 minutes before slicing into squares. Serve warm for best flavor, with optional vanilla ice cream accompaniment.