In large saucepan place turkey giblets and neck, 1/4 cup water, onion, celery, salt and bay leaf. Bring to boil, cover and simmer 30 minutes or until giblets are tender.
Drain broth, reserve. Pour pan drippings into large measuring cup. Allow to stand several minutes until fat separates from turkey juices.
Return 6 tablespoons fat drippings to pan, discard remaining fat drippings.
Add reserved giblet broth to turkey juices to equal 6 cups. Return to roasting pan. Stir together cornstarch and water until smooth, add to roasting pan.
Add bouillon cubes, stirring constantly. Bring to boil over medium heat, stirring up brown bits from bottom of pan. Boil 1 minute. If desired, chop giblets and add to gravy. Makes 6 cups.