Instructions:

Cook the hamburger with the onion and drain the grease. Grease a 9-inch by 13-inch pan and preheat the oven to 350 degrees. Pour one jar of the spaghetti sauce in the baking pan. Add the cooked spaghetti, and hamburger mixture. Dollop the sour cream on top of this layer. Sprinkle half of the cheese on this layer. Pour remaining jar of spaghetti sauce on this layer and follow with the rest of the Mozzarella cheese. Cover with foil and bake at 350 degrees for 45-55 minute or until thoroughly cooked.