A tasty variation on the Croque Monsieur is the Croque Madame.

A fried egg (the sunny side up kind) is placed atop the grilled ham and cheese sandwich when it comes out of the oven. This is essential: the two are prepared seperately. They are joined at the last minute, and a master chef will time it so both the sandwich and the egg are ready at the exact same moment. Salt and lots of pepper is used for seasoning.