Pick most of the meat off the chicken bones (leave a little for flavour) and arrange the bones, wings, skin & everything on a roasting tray.
Scatter your washed (unpeeled) halved carrots, unpeeled quartered onions, unpeeled garlic cloves and quartered celery over the top of the bones and drizzle with the olive oil.
Roast in the centre of the oven for 45 minutes.
Transfer the roasted bones and vegetables to a large stock pot. Add the parsley, pepper corns, apple cider vinegar and enough water to cover.
Bring to the boil, reduce the heat to low and simmer with the lid on for several hours.
Strain through a colander, reserving the liquid.
Drink hot, or use in soups and stews. Freezes well.