Preheat the oven at 160ºC/320ºF conventional oven and line a 12-cup cupcake tray with 12 cupcake liners.

In a large bowl, sift the granulated sugar, brown sugar, all-purpose flour, baking powder, baking soda and salt. Give it a stir to make sure everything has been combined. Set it aside.

In another mixing bowl add the sour cream and Biscoff spread and mix them together.

Then add whole milk, vegetable oil, eggs and vanilla extract and mix it all together until combined.

Pour the wet ingredients into the dry and gently stir it all together. Make sure there are no lumps left in the batter.

Divide the cake batter into the 12 cupcake liners and bake them for 20-23 minutes. Let the cupcakes cool in the hot pan. After 5 minutes, gently remove the cupcakes from the cupcake pan and let them cool down completely on a wire rack.

WAIT UNTIL CUPCAKES HAVE COOLED BEFORE STARTING THE ICING!

For the buttercream, mix the butter until light and fluffy in a stand mixer with the paddle attachment or with a hand mixer on medium/high speed.

Then add the Biscoff spread and mix it.

Scrape down the sides of the bowl and add the powdered sugar, vanilla extract and milk in 2 parts. Mix on low speed until each addition is fully incorporated. Scrape down the bowl and continue mixing for 1 minute.

Add the Biscoff buttercream to a piping bag with a round piping tip e.g. a Wilton 1A. Then pipe the buttercream on the cupcakes, creating a small concave with the buttercream.

In a microwave safe bowl, melt Biscoff spread for 10-20 seconds in the microwave until it is fluid. Pour the Biscoff spread into the middle of the buttercream and drizzle with any excess over the cupcakes. Optionally, decorate the cupcakes with Biscoff cookie crumbs.