A tuna melt sandwich is a type of sandwich consisting of bread, tuna with mayonnaise and a layer of cheese, sometimes grated. The sandwich is then grilled or fried until the cheese is melted. It may be served as an open face sandwich or a closed face one. Other popular choices are ham, roast beef, chicken, turkey, and a hamburger patty, which is known as a patty melt. It is the filling that establishes the melt sandwich as a variation of the grilled cheese sandwich.