In a large bowl, combine the first 7 ingredients. Crumble beef and sausage over mixture and mix lightly but thoroughly. Shape into 1/2-in. balls. , In a Dutch oven, brown meatballs in small batches; drain. Add the broth and pepper; bring to a boil. Reduce heat; simmer, uncovered, for 10 minutes. Stir in chicken and pasta; cook 5-7 minutes longer or until pasta is tender. Stir in spinach; cook until wilted. Sprinkle with shredded Parmesan cheese if desired. Freeze option: Before adding cheese, cool soup. Freeze soup in freezer containers. To use, partially thaw in refrigerator overnight. Heat through in a saucepan, stirring occasionally; add broth or water if necessary. Sprinkle each serving with cheese.