If using heritage roasting chickens, preheat the oven to 325 F degrees, place the two roasting chickens breast down in a graniteware roaster, add water to approximately 1" deep in the roasting pan, and roast for 30 minutes per pound (i.e. if using 4 lb. birds, roast for 2 hours), or until cooked through. Allow to cool, remove chicken from bones and shred, and discard skin and bones (or save for making chicken stock). Pour the collected liquid from the bottom of the roaster into a large measuring cup, refrigerate to separate the fat from the broth, skim and discard fat, and reserve broth for another use.