Overview
A croque monsieur is a hot sandwich made with ham and cheese. The name comes from the French words ("crunch") and ("gentleman").
History
There are references to the dish before the end of the 19th century. In 1891, mentions them:
In the early 1900s, bistro owner Michel Lunarca popularized the croque-monsieur.
Preparation
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.
From Wikipedia (CC BY-SA 4.0).