Fluffy Bacon-Cheese Frittata

In a skillet, cook bacon over medium heat until crisp; remove to paper towels. Drain, reserving 1 tablespoon drippings. In the drippings, saute onion until tender. Remove from the heat; set aside. In a large mixing bowl, beat egg yolks, milk, flour and paprika until smooth. Add Swiss cheese. In a small mixing bowl, beat egg whites and salt until stiff peaks form. Fold into cheese mixture. Pour over onion in skillet; cover and cook on medium-low heat for 12-15 minutes or until almost set. Sprinkle with cheddar cheese and bacon. Cover and cook 5 minutes longer or until cheese is melted. Sprinkle with parsley. ');