Chicken Stock

Name: Chicken Stock
Yield: Makes 4 quarts
Ingredients: 1 unpeeled white onion, halved; 1 carrot, roughly chopped; 4 celery ribs, roughly chopped; 1 tablespoon black peppercorns; 1 fennel bulb, roughly chopped; 5 sprigs fresh thyme; 2 chicken carcasses; 2 bay leaves; 6 quarts water; ¼ cup parsley stems