Using ground chicken breast makes the meatballs lower in fat than when using ground beef. If you can't find it, substitute ground turkey breast. This recipe teaches uniformity of size to ensure that all of the meatballs finish cooking at the same time.
To prepare meatballs, combine the first 10 ingredients in a bowl; shape mixture into 48 (1-inch) meatballs. Place meatballs on a jelly-roll pan coated with cooking spray. Bake at 400° for 20 minutes or until done.
To prepare soup, bring water and broth to a boil in a Dutch oven. Add celery, onions, and frozen vegetables; cook 10 minutes or until vegetables are tender. Add pasta; cook 8 minutes or until done. Add meatballs; cook 2 minutes or until thoroughly heated. Place 6 meatballs in each of 8 bowls; divide soup among bowls. Sprinkle evenly with parsley.