Rinse and dry the chicken thoroughly. In a large heated soup pot, place the onions, celery, carrots, and bay leaves. Add the whole chicken to the pot, and cover with enough cold water to cover almost all of the chicken. Add the tomatoes. Bring it pot up to the boil. When pot is at full boil, turn the heat down to low. Remove the scum of the broth as it forms on top with ladle. Allow to simmer for a couple of hours.
Bring large pot of salted water to boil, add pastina and cook according to package directions.
Remove the chicken from the broth and set aside. Place a strainer over a large serving bowl and strain the chicken broth through. Strain pastina well, before adding into the bowl with the broth. Serve immediately, top with grated Parmesan, if desired.