Preheat the oven to 350°F (175°C) and line a muffin tin with cupcake liners.

In a large bowl, combine the melted butter, cookie butter, granulated sugar, and brown sugar. Mix until smooth. Add in the eggs and vanilla extract, whisking until fully incorporated.

In a separate bowl, sift together the flour, baking powder, baking soda, and salt.

Gradually add the dry mixture to the wet mixture, stirring gently just until combined. Avoid over-mixing!

Spoon the batter into the prepared cupcake liners, filling each about 2/3 full. Optionally, sprinkle Biscoff cookie crumbs on top before baking.

Place the muffin tin in the preheated oven and bake for 18-20 minutes, or until a toothpick inserted into the center of a cupcake comes out clean.

Allow the cupcakes to cool in the pan for about 5 minutes before transferring them to a wire rack to cool completely.

Once completely cooled, frost with your favorite frosting. A cream cheese or buttercream frosting pairs beautifully with the flavor of cookie butter.