Heat oil in a saucepan over medium heat. Add onion and garlic and cook until the onion is soft,about 2 minutes. Stir occasionally.Add chicken broth, tomatoes, pasta, and parsley to the saucepan. Bring the liquid to a boil, reduce heat, and simmer for 10 minutes. Add broccoli, carrots, and celery to soup; cook 10 minutes. Add salt and pepper to taste. With adult help, ladle soup into serving bowl and sprinkle with Parmesan cheese before serving, if desired.