The Wikipedia article does claim that a monte cristo is “traditonally” deep fried. But then go read the sources they cite about the history of the sandwich.
Stradley’s “History of Monte Cristo Sandwich” in What’s Cooking America says “the basic sandwich is two slices of white bread containing ham, turkey, or chicken, and a slice of cheese are dipped in beaten egg and fried in butter” and “Most food historian generally think that the Monte Cristo sandwich is a variation of a French dish called Croque Monsieur. This original grilled cheese sandwich consisted of Gruyere cheese and lean ham between two slices of crust-less bread, fried in clarified butter. It was originally served in 1910 in a Paris cafe. This sandwich is still a popular snack or casual meal throughout France and Switzerland in most bars and cafes. It is usually made in a special sandwich grilling iron consisting of two hinged metal plates, each with two shell-shaped indentations.” And Stall and Spalding’s “The Monte Cristo Sandwich” in The Encyclopedia Of Guilty Pleasures: 1,001 Thing You Hate To Love described it as “basically a ham and/or turkey sandwich dredged in egg batter and fried in a skillet”.
Stradley’s book also offers the information that while the sandwich dates back to 1910, it became trendy when it became a featured menu item at the Blue Bayou and Tahitian Terrace restaurants in Disneyland in 1966. And the Disneyland recipe, which is cited, specifices deep frying with jelly on the side.
So all the people who think a monte cristo is supposed to be deep fried and served with jelly have been fooled by the Mickey Mouse version. A real monte cristo is pan-fried in butter with no sweet stuff.