What decides this sandwich happens before the cheese is ever a wheel, in the milk. Sheep's milk is fattier and higher in solids than cow's milk, which gives fromage de brebis a dense, almost waxy paste, a long buttery finish, and a sweetness underneath the salt that no cow's-milk cheese quite matches. Across the Southwest, in Basque and Béarnais country, and on Corsica, this is the cheese the fromagerie ages firmest: an Ossau-Iraty in the Pyrenees, a hard brebis tomme on the island. The sandwich is a split crusted loaf and a thick layer of it, and what lifts it above a generic cheese build is exactly that richness: the paste is dense enough to feel substantial and sweet enough to pair with things a sharper cheese would fight.
The build follows from the texture. Sheep's-milk tomme is firm and slices clean, so it is laid in shingles rather than spread, cut thick because the paste is mellow rather than aggressive and thin slicing wastes its body. Butter is rarely needed: the cheese carries its own fat and films slightly against the crumb as it warms in the hand. The classic counterweight is sweet rather than acidic, because the brebis sweetness invites it: a stripe of black cherry jam in the Basque manner, or chestnut honey, is the single addition that does the most work. The bread needs a real crust to hold a dense, fatty filling that brings no structure of its own, and the sandwich is eaten cold and soon, the cheese at room temperature so its long finish opens.
Variations stay on the sheep's-milk shelf. The same bread takes a young, milder brebis for a gentler read or a long-aged one for a sharper, more crystalline bite; the cherry jam swaps for fig or honey by region. A slice of air-dried ham laid alongside turns it toward a mixed build that the cheese's sweetness carries well. The Sandwich au Fromage de Brebis belongs with the cheese builds the catalog groups under Baguette Fromage. Its specific contribution to that shelf is the milk itself: a dense, sweet, fat-rich paste that pairs with jam rather than pickle and gives the sandwich a softer logic than its cow's-milk neighbors.