Juicy Lucy Burgers, oh my! We use to have these when I was a child and my mother stuffed them with a mixture of sauteed onions, cheese, ketchup and mustard. The were freaking amazing! Take two very thin beef patties, place cheese and stuffing on one then top with the other. Seal the edges and cook as usual. It helps to make the patties very thin and larger then usual as they shrink once cooked.