Preheat oven to 400 degrees F (200 degrees C).

Place bacon in a large, deep skillet. Cook over medium high heat until evenly brown. Drain, crumble and set aside.

In a large bowl, whip together eggs, cream, nutmeg, salt, and pepper. Stir in bacon, spinach, mushrooms, onions, 3/4 cup Swiss cheese, and 3/4 cup Cheddar cheese. Transfer to the pie crust. Top with remaining cheese.

Bake uncovered in the preheated oven 35 minutes, or until bubbly and lightly browned.