Cook vermicelli according to package directions, except omit any oil and salt. Drain well. Toss with egg white. Coat a 9-inch quiche dish or 9-inch pie plate with nonstick cooking spray. Press vermicelli mixture into bottom of prepared dish. Sprinkle with mozzarella cheese. Set aside.
Meanwhile, in a large skillet cook turkey sausage, mushrooms, onion, and garlic until sausage is brown and onion is tender. Drain off fat.
Stir in undrained tomatoes, tomato paste, Italian seasoning, and crushed red pepper. Pour sausage mixture over cheese layer.
Cover the dish loosely with foil. Bake in a 350 degree F. oven for 25 to 30 minutes or until heated through. Sprinkle with Parmesan cheese. Let stand for 10 minutes. If desired, garnish with celery leaves. Cut into wedges to serve. Makes 6 servings.