Brown the carcasses in a roasting pan in a hot oven. Drain off any fat.
Heat a large stockpot and sauté the onion, leeks, garlic and carrot in a little oil until softened.
Add the thyme, parsley, peppercorns and bay leaves and stir for a minute or two. Add the wine and allow to boil for a few minutes. Add the chicken stock, bring to a boil and simmer for