A basic definition is this: A farçon is made of potatoes (above all), pureed or grated and combined with eggs, milk, and, sometimes, bacon. Fresh or dried fruit, cabbage, and assorted herbs are often added. The ingredients may be cooked in a bain-marie or baked in the oven. It may be packed into a terrine or casserole dish, or cooked in a besace—a cloth sack soaked in bouillon.

But there isn't one recipe: There are literally dozens. Every village—every family, it sometimes seems—has its own method for preparing it. Some versions even omit the potatoes, like the farçon with a base of milk-soaked bread eaten in Sainte-Foy-en-Tarentaise, a village between Bourg-Saint-Maurice and Val d'Isere. The one thing everyone seems to agree on, though, is that farçon should be cooked long and slow. It is a Sunday dish, one that can be put in the oven before leaving for Mass. The longer the cooking, the better the farçon.