Tarte Flambé (Alsatian Bacon and Onion Tart)

Place bacon in a skillet and cook over medium-high heat until cooked but not crisp and fat has rendered out, about 8 minutes. Drain in a strainer; reserve fat.

Place skillet back over medium heat. Add sliced onions. Cook briefly just until they lose their raw edge and soften up slightly, 3 to 5 minutes. Add a teaspoon or 2 of bacon fat if the pan seems too dry. Remove the skillet from heat and allow to cool to room temperature.

Mix fromage blanc, crème fraîche, nutmeg, salt, black pepper, and cayenne pepper together in a mixing bowl.