Variations on a Croque...

Classic Croque Monsieur

The popular Croque-Monsieur, is a grilled ham and cheese sandwich with béchamel sauce Typically, Emmental or Gruyère cheese is used.  The sandwich's first recorded appearance in Paris, in a café on the Boulevard des Capucines. 
The name is based on the verb croquer ("to crunch") and the word monsieur ("mister"). A Frenchman spots his waiter, simply holds up his finger, and makes a concise request: “Sir, the  crunch" ("Le Croque, Monsieur!").

Classic Croque Madame

Then there's of course the Croque-Madame served with a fried egg or poached egg on top. Many dictionaries attribute the name to the egg resembling an old fashioned woman's hat.

A ham and cheese sandwich snack, very similar to the croque-monsieur, is called a tosti in the Netherlands, and toast (pronounced "tost") in Italy & Greece.

The Monte Christo

Similarly, in England a ham and cheese hot snack is called a 'toastie', and toastie makers areavailable to buy. In the United States, the Monte Cristo, a ham-and-cheese sandwich often dipped in egg and fried, is popular diner fare. A version of this sandwich in Spain replaces the ham with sobrassada, a soft sausage from the Balearic Islands that can be easily spread.
 

But that's not all...Add a tomato, and you have a croque Provençal.  Substitute blue cheese (from Auvergne) for the Gruyère, and you have a croque Auvergnat.  Finally, substitute (Norwegian) smoked salmon for the ham, and you have a croque norvégien. click on the links for the description an/or recipe.

Croque Provençal - (with tomato, basil)

Croque Auvergnat - (with bleu d'Auvergne cheese)

Croque Gagnet (with Gouda and andouille sausage)

Croque Norvégien (with smoked salmon instead of ham) 

Croque Boum-Boum (with Bolognese sauce) 

Croque Tartiflette (with sliced potatoes and Reblochon) 

Croque Señor (with tomato salsa) 

Croque Hawaiian (with a slice of pineapple) 

Croque McDo" sandwich at McDonald's locations in France 

from left to right croque provençal,croque norvégien,croque Boum-Boum,croque tartiflette, croque señor and the weird croque McDo