Pick off any bits of chicken you can and set aside in fridge to add back into the soup later.
Place the chicken carcass in a large soup pot, cover with water (about 1 1/2 litres) and add black pepercorns, chopped potato, carrots, celery and parsley. Bring to the boil, then allow to simmer for about 1–1½ hours.
Remove and discard the carcass. Then ladle the liquid into a sieve or colander,pushing through some of the soft vegetables to make a thicker stock, if you like; discard the rest.
Pour the liquid into a clean pot; reheat slowly and stir in cream and leftover pieces of chicken. Allow to simmer for a few minutes, then season with black pepper and garnish with fresh parsley or thyme.