Broccoli Quiche

one 9-inch pie crust (I like the deep dish ones)
1 cup chopped broccoli
1/2 cup chopped onion
1/2 cup chopped mushrooms
2 whole eggs plus 2 egg whites
1 teaspoon dried parsley
1/4 teaspoon black pepper
1/4 teaspoon salt (optional)
 3/4 cup milk
3/4 cup shredded Swiss or mozzarella cheese (I usually use the mozzarella)
2 tablespoons flour

 Preheat oven to 400 degrees. Bake pie crust for 5 minutes; remove from oven and set aside. Decrease oven temperature to 350 degrees. Combine whole eggs and egg whites and beat together. Add broccoli, onions, mushrooms, salt, pepper, and parsley; stir together gently. Add milk, cheese, and flour. Stir mixture together and pour into warm pie crust. Bake for 35-40 minutes or until knife inserted into center comes out clean.