Preheat the oven to 500 degrees F. Cook the bacon in a medium skillet over medium heat until crisp, about 12 minutes. Transfer to a paper-towel-lined plate with a slotted spoon. Cook the leeks in the bacon fat, stirring, until tender but not browned, about 5 minutes. Season with salt and pepper.
Lightly oil a 12-by-17-inch baking sheet. Place the dough on top and gradually press and stretch to fit the pan. Sprinkle the cheese evenly on top, followed by the leeks and bacon. Bake until the crust is golden brown, 12 to 15 minutes. Transfer to a cutting board and cut into pieces. Sprinkle with a little freshly grated nutmeg.
Cook's note: You can buy prepared pizza dough in many pizza shops or grocery stores.