Step 1

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 the fat.

Step 2

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 pan seems too dry. Remove skillet from heat and allow to cool to room temperature.

Step 3

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

Step 4

Place 1 ball of pizza dough on a well-floured surface. Flatten and roll out to a 10- or 12-inch thin circle. Transfer to a cold cast iron pan. Heat over medium-high heat to pre-cook the bottom of the crust. As dough heats and bubbles appear, deflate them with the tines of a fork so crust ends up thin and crisp (not chewy). When bottom is nicely browned and just about to start getting charred, 5 to 7 minutes, remove from heat. Repeat with remaining dough.

Step 5

Spread a generous amount of cheese mixture over the crust. Top evenly with some onions and then the bacon. Broil 5 or 6 minutes until edges are browned and starting to lift. Repeat for remaining tartes.