Boil noodles until tender; drain. Cook ground beef and onion in skillet until browned. Drain fat. Stir in tomato sauce and spaghetti sauce mix. Cook until thickened. Combine cream cheese and evaporated milk in saucepan and cook on low heat until mixture is smooth. Stir in noodles and garlic salt. Pour mixture into a greased 9" square baking dish. Spread on meat mixture. Top with Mozzarella cheese. Bake at 350F degrees for 20 minutes or until bubbly.