Preheat your oven to 350°F (175°C) and grease or line a 9x9-inch baking pan with parchment paper.

Melt the unsalted butter and Biscoff cookie butter in a medium saucepan over low heat, stirring continuously until smooth (about 5-7 minutes).

Whisk in the brown sugar until well blended, creating a glossy base for your blondies.

Add eggs one at a time, whisking vigorously after each addition, then stir in the vanilla extract.

Sift together the flour, baking powder, and salt in a separate bowl, then gently fold into the wet ingredients until just combined.

Fold in the white chocolate chips and crushed Biscoff cookies for added texture and flavor.

Pour the batter into the prepared pan and spread evenly. Bake for 25-30 minutes or until the edges are golden and a toothpick comes out with a few moist crumbs.

Let cool in the pan for 10 minutes, then lift out and cool completely on a wire rack. Cut into squares and enjoy!