I made this for my husband's birthday. The 'bun' is 2 spice cakes- the bottom baked in an 8 inch round, and the top baked in a round casserole dish. The seseme seeds are buttercream frosting. The hamburger is brownie, and the lettuce, tomato, and cheese are fondant. I used buttercream for the ketchup and mustard. It was a fun cake to do, and one of the easiest so far (in my limited experience at least).