Line a deep-dish 9-in. pie plate with pastry. Trim and flute edge. Line unpricked pastry shell with a double thickness of heavy-duty foil. Bake at 450° for 5 minutes. Remove foil; bake 5 minutes longer. Place on a wire rack. Reduce heat to 350°.
In a skillet, saute the onion in butter until tender. Stir in spinach. Remove from the heat. Sprinkle cheese and bacon into crust; top with spinach mixture. In a bowl, beat eggs. Add the cream, salt and pepper; mix well. Carefully pour into crust.
Bake at 350° for 45-50 minutes or until a knife inserted in the center comes out clean. Let stand for 10 minutes before cutting.