Hubby asked for a "Cheeseburger Cake" for his birthday. I made 2 1.5 lb hamburgers baked in the oven in cake pans. I layered up the cake with cheese and his favorite cheeseburger toppings. Then I laid out a pinwheel of giant cheese slices and left it in a warm oven just long enough for the cheese to melt into a "frosting" like shape. I think this would have been better done with a blowtorch (targeted and controlled heat.)
I used 3 lbs hamburg and 1.5 lbs of cheese, and generous quantities of relish, mustard, and ketchup. We served lettuce and tomatoes on the side, but most guests ignored them.
Review: Not too hard to make, tasty, looks vaguely like cake, holds candles just fine. Might look more cake like with a third layer. Leftovers served well as quick meals, although the cheese melted all over the plate upon microwaving.