When we visit my wife's family in Worthington, OH, I usually end up eating breakfast at La Chatelaine, a French bakery and cafe. They serve something called a Croque Monsieur, which is basically an open hot ham and cheese sandwich, with Bechamel sauce.
The apocryphal origin of this sandwich goes like this. In the early 20th century, some Parisian workers accidentally left their lunch pails near a hot radiator, and they found their ham/cheese/butter sandwiches all crisped and delectable. Cafes started serving them with the name Croque Monsieur, or Crispy Mister.
A few weekends ago, I decided to make one of these suckers. The recipe called for a Swiss cheese, like Gruyere, to make a white cheese sauce. Which means you're basically making the Bechamel (a milk based sauce which uses flour as the thickening agent) and stirring in the grated Swiss cheese. So you toast some French bread, put a slice of ham on top, and pour the cheese sauce over it. Then broil. And, fearing this wouldn't be rich enough, I decided to add some extra cholesterol on top in the form of an over-medium fried egg.