Mash Roquefort with a fork and a little butter and you have the filling for this sandwich already made. Roquefort is a sheep's-milk blue from the Aveyron, cave-ripened with Penicillium roqueforti in blue-green veins, sharp and salty and soft enough at room temperature to work into a paste. Spread thick on a split baguette, it needs almost nothing else.
The paste approach is the point of this version. Crumbled Roquefort gives bursts of salt against plain bread; worked smooth with beurre demi-sel, it becomes a single even layer that coats the crumb and reads rounder, the butter taking some of the edge off the piquant blue without hiding it. The bread has to be firm-crusted, because the filling brings no structure and a soft loaf goes slack under the salt and the fat.
A few crushed walnuts pressed into the paste add a bitter crunch the blue welcomes; a thin film of honey pulls against the salt. Neither is required. This is the spreadable, fork-and-butter reading of the Roquefort sandwich, and it sits with the cheese builds the catalog groups under Baguette Fromage.