The Sandwich Vendéen speaks in a Vendée register, and the register is the whole point. The defining pairing is jambon de Vendée, the regional ham cured and often seasoned with a little eau-de-vie and herbs, and mogettes, the white coco beans of the Vendée cooked soft and creamy. The bread is local: frequently the Vendée brioche, the lightly enriched, faintly sweet loaf the region is known for, though a sturdy crusted bread does the same job in a plainer key. The build is the split loaf, butter or none, slices of the regional ham, and the mogettes crushed or left whole and worked through, with maybe a leaf of green for snap. The discipline is to keep it regional rather than generic, because the parts are what mark it as Vendée and not anywhere else.
The logic is a regional ham and a soft white bean working as a pair rather than as a meat with a side. The mogettes, crushed, behave almost like a mild spread that beds into the crumb and bridges the ham to the bread; left whole they add a soft starchy body that fills the sandwich without dominating it. The ham brings the salt and the cure, the beans bring the calm, and the balance between them is the sensory event. The bread choice is structural: the Vendée brioche is tender and faintly sweet, which flatters the savoury ham and the gentle bean but goes slack if the filling is too wet, so the mogettes want to be drained well rather than loose. A plain crusted loaf takes a heavier hand and stays distinct longer. Temperature is forgiving here, since neither ham nor cooked bean needs heat, which makes this a sandwich that travels better than most regional plates.
Variations stay inside the Vendée and the wider regional larder rather than wandering off it. The neighbouring regional sandwiches each speak their own dialect of ham, bean, and local bread, and those deserve proper attention of their own rather than being crowded in here. Within the Vendée version the turns are small: brioche against a plain crust, mogettes crushed against whole, a thin layer of regional butter, a leaf of frisée for bite. The Sandwich Vendéen belongs with the place-named builds the catalog groups under Regional Specialty Sandwiches, each a small argument about how a corner of France eats. Its specific contribution is jambon de Vendée and mogettes on a regional, often brioche, loaf, a ham-and-bean pairing carried in a faintly sweet bread, and the cook's job is to keep the parts local and the beans drained.