1.Cook Spaghetti According To Package Directions; Drain. In A Bowl, Combine The Egg, Parmesan Cheese And Spaghetti. Press Spaghetti Mixture Onto The Bottom And Up Sides Of A Greased Shallow 2-Cup Baking Dish Or 7-In. Pie Plate. Spread With Sour Cream. 2.Crumble Turkey Into A Skillet; Add The Pepper, Onion And Butter. Cook Over Medium Heat Until Meat Is No Longer Pink; Drain. Stir In The Tomato Sauce, Garlic Salt, Oregano, Salt And Pepper. Spoon Into Spaghetti Crust. Sprinkle With Mozzarella Cheese. Cover Edges Loosely With Foil. Bake At 350 Degrees F For 15-20 Minutes Or Until Heated Through And Cheese Is Melted. Serve Immediately.