Line the unpricked pie crust with a double thickness of foil. Bake in a 450 degree oven for 8 minutes. Remove foil. Bake 4 to 6 minutes or until pie crust is golden. Remove from the oven. Reduce oven temperature to 325.
Meanwhile, in a large skillet cook the bacon till crisp; drain, reserving 2 tablespoons drippings. Crumble bacon; set aside. Cook sliced onion in reserved drippings till tender but not brown; drain.
In a medium mixing bowl stir together the eggs, cream or milk, salt and nutmeg. Stir in the crumbled bacon and onion. Toss together shredded cheese and flour. Add to egg mixture; mix well.
Pour egg mixture into hot pastry shell. Bake in a 325 degree oven for 35 to 40 minutes or till a knife inserted near the center comes out clean. If necessary, cover edge of crust with foil to prevent over browning. Let stand for 10 minutes before serving.