Most cheese sandwiches present the cheese; a Sandwich au Maroilles often has to disguise it, because the cheese is too strong to meet head-on. Maroilles is a washed-rind cow's-milk cheese from the Nord, brick-orange and repeatedly washed until the paste is soft, glossy, and ammoniac, with a savory, almost beefy force that carries across a room. The workable build does not slice it cold but warms it across split crusted bread over a base of butter until it goes molten and tart, the way it behaves baked into the region's cheese tart.
The work is in heat and proportion, not addition. Warmed, the rind's sharp ammonia softens and the paste reads roasted and savory instead of relentless; the butter underneath cushions the salt and spreads the melted cheese evenly rather than leaving it in hot pockets. Too much cheese, or too much heat, and it breaks oily and dominates anyway. The bread needs a firm crust because the filling is soft and structureless, and it is best warm rather than hot. A few thin slices of ham folded under the cheese, the old working build of the Nord, is as far as it usually needs to go.
The Sandwich au Maroilles sits with the regional-cheese builds the catalog groups under Baguette Fromage. Its specific contribution is a cheese so pungent that the sandwich's real technique is melting it into submission.