Bring eggs, butter, and Biscoff spread to room temperature before mixing to ensure smooth emulsification and even distribution of flavors throughout the batter.

Drop spoonfuls of Biscoff spread onto the batter and swirl gently with a knife rather than fully blending to create distinct pockets of cookie butter that stay fudgy and gooey.

Remove brownies when a toothpick inserted in the center still has moist crumbs clinging to it—they'll continue cooking as they cool, resulting in that perfect fudgy texture.

Reserve half the crushed Biscoff cookies to fold in at the end and sprinkle on top before baking, preserving their texture and creating delightful cookie pieces throughout.

Use roughly equal parts butterscotch and semisweet chocolate chips but add the chocolate chips last, coating them lightly in flour to prevent sinking to the bottom during baking.