Place bacon in a large, deep skillet. Cook over medium high heat until evenly brown. Drain, crumble and set aside. Preheat oven to 450 degrees F (230 degrees C).
Line a large pie pan or quiche pan with the pie shell. Brush shell with melted butter. Sprinkle bacon in bottom of pie pan.
Beat eggs with cream, salt, sugar, nutmeg, cayenne pepper and black pepper. Sprinkle the grated cheese over the bacon and then sprinkle the crab meat and shrimp over the cheese. Pour the egg mixture over everything and arrange the mushroom slices over the egg mixture.
Bake in preheated oven for 10 minutes, reduce heat to 350 degrees F (175 degrees C) and continue baking until set, about 25 to 30 minutes. Let cool for 10 minutes before serving.