You will need one loaf cake or alternatively an oblong or square cake and one round cake.
Cut the square or oblong shape cake in half to make two long pieces and remove the centre piece of the circular cake. You can do this by using a glass to trace a centre piece which you can remove.
Resource: See cutting a zero cake
Use the edge of the round cake as a guide to cut a piece from the bottom of one of the long pieces of cake.