Preheat oven to 230 C. Line pastry shell with foil and some beans or rice as a loading. Bake in preheated oven for 8 minutes. Remove foil and bake for an additional 5 minutes or until crust is set and dry. Remove from oven and turn down temperature to 170 C.
In a large frying pan, cook bacon until crisp. Drain and reserve 2 tablespoons of drippings. Crumble the bacon and set aside. Cook onion in pan in the bacon fat until onion is tender. Remove and set aside.
In a large bowl, mix together milk, salt and eggs. Stir in bacon and onion. In a separate bowl, toss cheese and flour together, then add to egg mixture. Be sure to mix well. Pour egg mixture into pie crust.
Bake in preheated oven for 35 to 40 minutes, or until knife inserted in centre of the quiche comes out clean. If necessary, cover edge of crust with foil while baking to prevent burning or overbrowning. Let stand for 10 minutes before serving.