Directions:
Preheat oven to 400 degrees. Sauté onions in butter until slightly limp. Place in pie shell; top with Swiss cheese. Combine eggs, half and half, salt, dry mustard, cayenne pepper and pour over cheese; top with Parmesan and paprika.
Bake at 400 degrees for 15 minutes; reduce heat to 325 degrees and bake an additional 20 to 25 minutes, or until a knife inserted in the center comes out clean.