Snap the celery in half, cut the carrot and onion in half and add all 3 veg to a large pan.
Place the chicken carcass and all the removed pieces into the pan along with the bay leaves parsley stalks and peppercorns.
fill up with cold water so everything is submerged and cover with a lid.
Heat to a boil, then gently simmer for 90 minutes, removing the two legs and two breasts after 30 minutes of simmering. Top up with more water if the carcass becomes uncovered as the water evaporates.
Drain the chicken stock pan through a fine sieve to get chicken stock, all the bits can be thrown away now.