Tuna casserole is a casserole mainly composed of egg noodles (or some other starch such as rice) and canned tuna fish, with canned peas and corn sometimes added. The casserole is often topped with potato chips, corn flakes or canned fried onions. It is a common dish in some parts of the United States. Tuna casserole is convenient to the extent that it may be prepared using no fresh ingredients.