A croque monsieur (, croque = "crunch", monsieur = "mister, gentleman") is a hot sandwich made with ham and cheese.
There are references to the dish before the end of the 19th century. In 1891, mentions them:
A croque monsieur is traditionally made with baked or boiled ham and sliced cheese between slices of pain de mie, topped with grated cheese and lightly salted and peppered, and then baked in an oven or fried in a frying pan. The bread may optionally be browned by grilling after being dipped in beaten egg. Traditionally Gruyère is used, but sometimes Comté or Emmental cheese as well. Some brasseries also add béchamel sauce.
Croque monsieur may be baked or fried so that the cheese topping melts and forms a crust.
A croque monsieur served with a poached or lightly fried egg on top is known as a croque madame (or, in parts of Normandy, as a croque-ÃÂ -cheval). According to the Petit Robert dictionary, the name dates to around 1960. The name croque-mademoiselle is associated with its lighter, vegetarian version: made of the same bread, but with ordinary melting cheese, accompanied with chives, cucumber and lettuce.
In the United States, the Monte Cristo (a ham-and-cheese sandwich often dipped in egg and fried) is popular fare in diners.
Variants of the sandwich with substitutions or additional ingredients are given names modeled on the original croque-monsieur, for example: