Take the cupcakes and cut off the bumps so that they're left with nice flat tops.

Place the cupcakes on top of the rectangle sponge cake, so that it's laid out like a lego brick.

Mix together the frosting with a few drops of red food colouring until it becomes the desirable, Lego red colour.

Spread the bottom of the cupcakes with frosting and stick them in place on top of the cake.

Cover the whole cake neatly in frosting and it's ready to serve.