Start to finish: 1 hour 15 minutes
Servings: Makes three 10- x 12-inch pizzas
6 ounces bacon, sliced thin crosswise
4 cups thinly sliced onion
salt and black pepper
8 ounces crème fraiche
1 large egg yolk
3 ounces coarsely grated gruyere cheese
Pizza dough (recipe below) or 1 ½ pounds store bought pizza
Preheat the oven to 500 F. and arrange one of the oven racks on the bottom shelf of the oven.
In a large skillet cook the bacon over medium heat, stirring, until it starts to brown, 5 to 8 minutes. Transfer the bacon to paper towels to drain and pour off all but 2 tablespoons of the bacon fat from the skillet.
Add the onion to the pan, and cook, covered, over medium heat, stirring occasionally, until very soft, about 10 minutes. Remove the cover and cook, stirring occasionally until golden, about 20 minutes. Season with salt and pepper and set aside.
In a small bowl stir together the crème fraiche, egg yolk, nutmeg and salt and pepper.
Roll out one third of the dough on a lightly oiled surface into an 1/8-inch thick rectangle and transfer to a 15- by 17- inch piece of parchment. It will shrink and lose its shape so roll it again into the rectangle shape on top of the parchment. Place the parchment sheet on top of a baking sheet spread one third of the crème fraiche mixture evenly on the dough, top with one third of the onion and bacon and sprinkle one third of the cheese over the whole surface.
Repeat with the remaining dough, Crème fraiche mixture, onion bacon and cheese to make 2 more pizzas. Working in batches, bake on the lower shelf of the oven for 10 minutes or until the crust is crisp. Serve right away.