Quiche Lorraine, Vegetarian

Ingredients

• 1 deep 9" pie tin, lined with an unbaked pastry shell
• 4 large or extra large eggs, plus 1 extra egg white
• 1-1/2 cups (6 ounces) freshly grated Gruyere cheese
• 1/4 cup freshly grated Parmesan cheese
• 1 tablespoon all-purpose flour
• 1/2 pound diced soy Canadian "bacon"
• 2 tablespoons butter
• 1 large onion, peeled, sliced, and separated into rings
• 1 3-ounce can (1/2 cup) broiled, sliced mushrooms in butter sauce, drained
• 1-1/2 cups heavy cream
• 1/2 teaspoon salt
• 1/8 teaspoon ground nutmeg
• Pinch of cayenne pepper