Step 1:Preheat the oven to 180°C (160°C fan, gas 4). Line a cupcake tin with 12 paper cupcake cases.Step 2:Beat together the butter and sugar until light and fluffy. Gradually add in the eggs, baking powder, flour and vanilla extract and beat until fully combined. Step 3:Spoon the mixture into the cupcake cases filling each of them 2/3 full.Step 4:Bake for 20-25 minutes until the cupcakes are golden and springy to touch.Step 5:Whilst the cupcakes are baking make the buttercream by beating together the butter, icing sugar, milk and Biscoff spread. The longer that you beat the buttercream the lighter and fluffier it becomes.Step 6:When the cupcakes have cooled fully use a small sharp knife or an apple corer to carve out the centre of the sponge of each cupcake. Fill a piping bag with a large star nozzle and the Biscoff buttercream. Pipe a small amount into the centre of each cake then top with the remaining sponge that you had removed. Step 7:To finish your cupcakes, pipe swirls of the buttercream on to the top of each cupcake. For an extra touch add a Lotus biscuit on top of the buttercream.