Finely chop 2 tablespoons each of celery, carrot, onion and parsnip and set aside. Place large vegetable pieces, parsley, chicken (except reserved breast meat), peppercorns, bay leaves and salt in a large soup pot. Add 2 quarts of cold water.

Bring to a rapid boil; skim off any foam that rises to the surface, then lower to a gentle simmer. Cook 1 hour. Discard all cooked solids with a slotted spoon. Strain soup through a mesh strainer into a smaller soup pot.

Cut chicken breasts in half horizontally to make thin cutlets. Bring soup to a boil. Add chicken breasts and finely chopped vegetables to soup; cover and remove from heat. Allow to sit 10 to 15 minutes, until chicken is cooked through and vegetables are tender. Cut chicken into thin slices before serving.