In a small bowl, mix together salt, paprika, onion powder, thyme, white pepper, black pepper, cayenne pepper, and garlic powder
Remove and discard giblets from chicken
Rinse chicken cavity, and pat dry with paper towel
Rub each chicken inside and out with spice mixture
Place 1 onion into the cavity of each chicken
Place chickens in a resealable bag or double wrap with plastic wrap
Refrigerate overnight, or at least 4 to 6 hours
Preheat oven to 250 degrees F (120 degrees C)
Place chickens in a roasting pan
Bake uncovered for 5 hours, to a minimum internal temperature of 180 degrees F (85 degrees C)
Let the chickens stand for 10 minutes before carving
Aluminum foil can be used to keep food moist, cook it evenly, and make clean-up easier
