Tuna melt

A melt sandwich is a type of hot sandwich containing a suitable meltable cheese and a filling of meat or fish. The sandwich is grilled on the stovetop until the cheese melts (hence the name) and the bread is toasted, or heated in an oven. One common type is the tuna melt, a melt sandwich filled with canned tuna that has been mixed with mayonnaise (tuna salad) and other ingredients such as pickles, tomato, and onion. Other popular choices are ham, roast beef, chicken, turkey,[citation needed] or a ground beef patty (for a patty melt). Both patty melts and tuna melts are staples of the traditional American diner; patty melts were commonly found on menus by the 1940s, and tuna melts by the 1960s.

Source: Wikipedia