Make the basic stock:

To make the stock on top of the stove: In a tall narrow stockpot, bring the bones and 3 quarts water to a boil. Skim the fat.

Lower the heat and simmer gently, so bubbles are barely breaking the surface of the liquid, for at least 4 hours and up to 12; add water as needed to keep the bones covered. Skim as necessary to remove as much fat as possible.

To make the stock in the oven: Place a rack on the lowest level of the oven (remove any other racks) and heat the oven to 250°F.

In a tall narrow stockpot, bring the bones and 3 quarts water to a boil. Skim the fat. Place in the oven for 4 hours; add water if needed. Remove and skim the fat. Return to the oven for at least 5 hours, and up to 8.

To make the stock in a slow-cooker: Start with 2½ pounds bones and 6 cups water for a 4-quart cooker. Place the bones in the slow-cooker and pour the water over. Cover and turn the heat on low. Cook for 11 to 12 hours.

In all methods the bones will be falling apart when the stock is done. Strain the stock through a fine-mesh sieve. Skim the fat and cool to room temperature. Refrigerate for 3 hours.

Remove the fat from the top of the stock and the sediment from the bottom. Use immediately or refrigerate for up to 3 days or freeze. Makes 10 cups on top of the stove, 8 cups in the oven, 6 cups in the slow-cooker

Make the enriched stock:

Place the necks, hearts, gizzards, backs and wing tips from two 3-pound chickens in a saucepan. Add 3 quarts Basic Chicken Stock. Bring to a boil. Reduce the heat to a low simmer and cook as long as time allows— up to 18 hours. Top up the liquid from time to time with water, and skim regularly. Strain. Makes about 10 cups, depending on how long it cooks