Preheat your oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper.

In a mixing bowl, combine 1½ cups of crushed Biscoff cookies with ¼ cup of melted salted butter. Press into the bottom of the pan.

In a large mixing bowl, crack 2 eggs and add granulated and light brown sugars. Beat until light and creamy, about 2-3 minutes.

Pour in ½ cup of melted butter and 1 teaspoon of vanilla extract into the egg mixture. Mix until just combined.

Sift 1 cup of all-purpose flour, ¼ cup of unsweetened cocoa powder, and ½ teaspoon of baking powder together. Fold into the wet ingredients.

Pour the brownie batter over the Biscoff cookie crust and smooth the top.

Scoop ½ cup of smooth Biscoff spread into a microwave-safe bowl and microwave for 5-10 seconds. Drizzle over brownie batter and swirl.

Bake for 22-25 minutes. A toothpick inserted into the center should come out with a few moist crumbs attached.

Let the brownies cool for about 15-20 minutes. Refrigerate for cleaner cuts, then slice into squares.