Preheat your oven to 350°F (175°C) and line a 12-cup muffin pan with cupcake liners.

In a large mixing bowl, sift together flour, baking powder, baking soda, salt, and Biscoff cookie crumbs.

In a separate bowl, beat together softened butter and granulated sugar until light and fluffy, then add sour cream and vanilla.

Incorporate eggs one at a time, mixing well after each addition.

Gradually mix the dry ingredients and buttermilk into the butter mixture until just combined.

Fill each cupcake liner about 2/3 full and bake for 18–20 minutes or until a toothpick comes out clean.

Cool in the pan for 10 minutes, then transfer to a wire rack.

Once cooled, remove a portion from the center of each cupcake and fill with warm Biscoff cookie butter.

To make frosting, beat together butter and Biscoff cookie butter, then mix in powdered sugar, vanilla, and salt until fluffy.

Pipe frosting onto cooled cupcakes and drizzle with additional Biscoff cookie butter.