The Croque-Raclette is the croque-monsieur built around the one cheese engineered to melt. Raclette is a semi-firm Alpine cheese whose entire culinary identity is its behavior under heat: it goes liquid evenly, browns without seizing, and stays stretchy rather than greasy. Dropped into the croque format it does the job the béchamel normally does, binding the sandwich into a single mass, which is why most Croque-Raclette versions skip the white sauce entirely. The cheese is the sauce.
What this produces is a sandwich with very little internal contrast and a great deal of richness, which is the point rather than a flaw. The supporting ingredients exist mainly to cut through the cheese: cornichons, pickled onions, a few slices of jambon or air-dried ham, sometimes a turn of black pepper or a scrape of mustard on the bread. The pain de mie has to be sturdy and is usually toasted on the outside before assembly so the base does not collapse under a layer of molten raclette. This is winter food, and it carries the same après-ski association as the cheese's namesake dish, the table-side raclette grill.
The Croque-Raclette is one of several Alpine croques that rebuild the Parisian original around a single regional cheese. The Croque-Savoyard reaches for Reblochon or Beaufort; the Croque-Tartiflette adds potato to the same idea. The broader Croque-Monsieur tradition, including the béchamel-and-broiler logic these variants all descend from, has its own article. The raclette version's specific contribution is meltability taken to its limit: a croque where the defining technical decision is to let one purpose-built cheese do every job at once.