Preheat oven to 325°F.
Cook the shallot in the 2 T butter until tender.
Stir together the eggs, cream, milk, salt, lemon peel, and nutmeg. Add the onion and crab meat.
Combine the Swiss cheese and flour, then add to egg mixture.
Prepare the single pie crust. Remove pie crust from oven after 15 minutes and pour seafood mixture into the hot pastry shell. Return to oven and bake for 35-40 minutes, or till a knife inserted near center comes out clean. Allow to stand for 10 minutes.