Makes 3 tarts
1/2 cup crème fraîche (or sour cream)
1 cup cream cheese at room temperature
1⁄ 8 tsp. nutmeg, freshly grated
1 tsp. kosher salt, plus more to taste
Freshly ground white pepper, to taste
1 3⁄4 cups flour, plus more for dusting
1 tsp. baking powder
3 tbsp. olive oil
2 egg yolks
½ cup water
8 strips smoked bacon, finely chopped
1 medium white onion, thinly sliced

Heat an oven to 500° with a pizza stone positioned on center rack.
Mix crème fraîche, softened cream cheese, nutmeg, and salt and white pepper in a bowl. Set aside.
Whisk flour, baking powder, and 1 tsp. salt in a bowl; make a well in the center. Whisk oil, yolks, and 1⁄2 cup water in another bowl, and pour into well. Using a fork, stir until a loose dough forms. Turn out onto lightly floured surface; knead dough for 1 minute. Divide dough into 3 pieces. Working with 1 piece of dough at a time, roll into a 12" circle, and place on a parchment paper—lined baking sheet.
Spread 1⁄2 cup cheese mixture over circle, leaving a 1⁄2 " border around edge.
Sprinkle with a little of the bacon and onions. Transfer dough (on parchment paper) to pizza stone. Bake until lightly browned and crispy, 12-15 minutes. Repeat.