Line unpricked pastry shell with a double thickness of heavy foil.

Bake in a 450 degree oven for 8 minutes.

Remove foil. Bake for 4 to 5 minutes more.

Remove from oven. Reduce oven temperature to 325 degrees.

(Pie shell should still be hot when filling is added; do not partially bake pastry shell ahead of time.)

Meanwhile in a large skillet cook bacon until crisp. Drain, reserving 2 tablespoon drippings.

Finely crumble bacon; set aside.

Cook sliced onion and mushrooms in reserved drippings over medium heat until tender but not brown; drain.

In a medium bowl, stir together the eggs, half-and-half, milk, salt and nutmeg.

Stir in the crumbled bacon and onion/mushroom mixture.

Toss together shredded cheese and flour. Add to egg mixture; mix well.

Pour egg mixture into hot, baked pastry shell.

Bake in the 325 degree oven for 50 to 60 minutes or until a knife inserted near the center comes out clean.

If necessary, cover edge of crust with foil to prevent over browning. Let stand 10 minutes.