Understood, I just found it really strange because I... don't...see the topping... at all?

I didn't know it was a running gag. Thank you for educating me.

Actually, looking at the pic a bit longer, I have to take back what I said and say that the fact that it looks like Lelouch is supporting himself with his left leg actually suggests that he's not dead, simply resting with his eyes closed. If he were dead, his leg would likely have slid down along the chess piece.