Quiche with spinach, bacon, onions and mushrooms

Ingredients

• 1 pie crust, rolled out and fitted into a 9? pie pan
• 3 eggs, beaten
• 1 1/2 cups milk
• 1 tablespoon oil
• 1 medium onion, minced
• 1 cup mushrooms, sliced
• 3 cups spinach, chopped
• 6 strips bacon, cooked and crumbled
• 1 1/2 cups cheese (Gruyere or Swiss), shredded
• 1 tablespoon flour
• Salt and Pepper, to taste