Preheat oven to 450 degrees. Bake pastry shell for five minutes. Remove from oven. Set oven temperature to 400 degrees. Fry bacon until crisp; drain, and crumble. Cook onion until transparent in small amount of bacon fat. Drain. Sprinkle bacon and onion over bottom of pastry shell. Cover with cheese. Blend together eggs, milk, and seasonings. Pour over cheese. Bake for 10 minutes. Reduce heat to 350 amd bake for 30 to 35 minutes longer or until a knife inserted in center comes out clean.