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

In a medium bowl, mix 1.5 cups of crushed Biscoff cookies with ¼ cup of melted and cooled salted butter until fully coated. Press into the bottom of the prepared pan to create a crust.

In a large mixing bowl, combine room temperature large eggs, ½ cup of granulated sugar, and ¼ cup of light brown sugar. Beat on high for about one minute until creamy and light in color.

Gradually add in ½ cup of melted cooled salted butter and 1 teaspoon of vanilla extract to the egg mixture. Mix on low until just combined.

Sift together ½ cup of all-purpose flour, ¼ cup of unsweetened cocoa powder, and ½ teaspoon of baking powder into the wet mixture. Fold gently until no streaks remain.

Pour the brownie batter over the prepared Biscoff cookie crust, spreading it evenly with a spatula.

Microwave ½ cup of Biscoff spread for about 5-10 seconds to soften. Spoon dollops over the brownie batter and swirl gently with a knife.

Bake for 22-25 minutes or until a toothpick inserted into the center comes out mostly clean with a few moist crumbs.

Let the brownies cool in the pan on a wire rack. Cool completely before cutting into squares.