Brown ground beef in large saucepan on medium heat. Drain fat. Add onion; cook and stir 2 to 3 minutes or until softened.
Stir in tomatoes, tomato sauce, Seasoning and stock. Bring to boil. Add lasagna noodle pieces; cook 6 to 7 minutes or until noodles are tender.
Ladle soup into serving bowls. Serve with dollops of ricotta cheese and sprinkle with shredded mozzarella cheese, if desired.