Line the unpricked pastry shell with a double thickness of heavy-duty foil. Bake at 450° for 5 minutes. Remove foil. Bake 5 minutes longer. Remove from the oven; reduce heat to 350°. Combine Swiss cheese, spinach, mushrooms and ham; sprinkle over crust. In a bowl, beat eggs, cream, flour and salt until smooth; pour over spinach mixture. Sprinkle with cheddar cheese. Bake for 40-45 minutes or until a knife inserted in the center comes out clean.