Turkey Bouillon Cubes

In a large pot, heat the oil. Add the turkey carcass and cook over moderately high heat, stirring, until golden, 10 minutes. Add the garlic, onion, carrots, peppercorns and parsley stems and cook, stirring, for 5 minutes. Add 2 quarts of water. Bring to a boil, scraping up any browned bits. Simmer until reduced to 1 1/2 cups, 40 minutes. Strain into a heatproof bowl and let cool. Season with salt and pepper and add the chopped parsley and chives. Pour into an ice cube tray and freeze. Once frozen solid, transfer to a sturdy resealable plastic bag.