In countries like the U.S., a casserole is a baked meal with three major components: a protein like chicken, turkey, ham, tuna, and so on, a carbohydrate source like potatoes, sweet potatoes, rice, or even bread, and some vegetables like canned peas or fresh broccoli.u003cbr/u003eu003cbr/u003eTypically, a casserole will also be topped, or its ingredients mixed, with some kind of sauce (like bechamel) or gravy, and it can also be topped with cheese.