Few cheeses refuse compromise the way this blue does, and every other choice in the sandwich bends to accommodate it. Roquefort is a sheep's-milk blue from the Aveyron, ripened in the limestone caves of the Combalou with the Penicillium roqueforti mould running through it in blue-green veins. It is sharp, intensely salty, and creamy to the point of being almost spreadable at room temperature. The build is a length of baguette, a thin spread of beurre demi-sel or none, and Roquefort either crumbled along the crumb or pressed into a rough paste with a fork.
The logic of the sandwich follows from how aggressive the cheese is. Roquefort does not sit politely beside other ingredients: it dominates, so the sandwich is mostly an exercise in giving it the right counterweights and then getting out of its way. The salt and the piquant blue need bread with enough body to absorb them, which is why a firm-crusted baguette works better than anything soft. Crumbled, the cheese gives sharp pockets against plain bread; mashed with a little butter into a paste, it spreads into a single even, savory layer that reads smoother and rounder. Either approach is valid, and the choice is mostly about whether you want the salt in bursts or in a continuous coat.
Because the cheese is so forward, the most useful additions are sweet or crisp rather than savory. A few walnut halves give a bitter crunch that the blue leans into. A thin layer of pear, fig, or a smear of honey pulls against the salt and rounds the whole sandwich without softening the cheese's character. A leaf of bitter green keeps it from going heavy. Each of these is optional; the sandwich is complete with bread, butter, and Roquefort alone, and the additions are there to widen it rather than to fix it.
Variations move along the blue-cheese rack and the sweet counterweight. A milder cow's-milk Fourme d'Ambert makes a gentler, rounder version for those who find Roquefort too pointed. A measure of honey or fig confit turns it toward the cheese-board end of the spectrum; walnuts and a sharper wheel push it the other way. It belongs with the cheese sandwiches the catalog groups under Baguette Fromage, and its specific contribution is a cheese assertive enough that the entire sandwich is organized around managing it.