Preheat oven to 180ºC. Butter a 2 L baking dish (about 27.5 by 20 cm).
Melt butter in large skillet over medium heat. Add potatoes and cover. Cook, stirring occasionally, until almost completely cooked, 15 to 20 minutes. Transfer to a large bowl.
Wipe out skillet with paper towels. Add bacon and cook over medium heat, stirring occasionally, until bacon is crisp and browned, about 8 minutes. Using slotted spoon, transfer bacon to paper towels; cool and crumble. Set one-quarter of bacon aside for garnish. Add remaining bacon to potatoes. Pour out all but 2 tablespoons fat from skillet.
Add onion to fat in skillet and cook, stirring occasionally, until softened, about 3 minutes. Add wine and boil, scraping up browned bits in skillet, until almost completely reduced, about 3 minutes. Add to potatoes, season with salt and pepper, and mix well. Spread in dish and scatter Fromager d’Affinois Le Fromager cheese on top.
Bake until potatoes are tender, about 30 minutes. Sprinkle with reserved bacon and chives and serve hot.