1. Preheat the oven to 350°F and grease two 8-inch round cake pans. Line the bottoms with parchment paper.

2. In a medium bowl, whisk together the flour, baking powder, and salt.

3. In a large bowl, beat the butter, brown sugar, and granulated sugar until light and fluffy.

4. Add the eggs one at a time, then mix in the vanilla extract and Biscoff spread until smooth.

5. Add the dry ingredients in batches, alternating with the milk and sour cream, and mix just until combined.

6. Divide the batter evenly between the prepared pans and bake for 28 to 32 minutes, or until a toothpick inserted in the center comes out clean.

7. Let the cake layers cool in the pans for 10 minutes, then transfer them to a wire rack to cool completely.

8. To make the frosting, beat the butter and Biscoff spread until creamy. Add the powdered sugar and heavy cream, then beat until fluffy and spreadable.

9. Place one cake layer on a serving plate, spread a layer of frosting over it, then add a smooth layer of Biscoff spread in the center.

10. Top with the second cake layer, frost the top and sides, and garnish with Biscoff cookies.

11. Chill the cake for 20 to 30 minutes before slicing for the cleanest layers.