Double-Rich Duck Stock - cooking recipe

Ingredients

1 -3 duck carcass, broken into smallish pieces (plus bones, any uncooked wing tips, etc)
3 -5 quarts duck stock (or use liquid from simmering duck before roasting)

Preparation

Place duck carcass pieces into a stockpot. Cover with enough stock or simmering liquid to cover bones by 1 inch. Cover and bring to a boil over high heat, skimming to remove scum that forms on surface.
Reduce heat to keep at a simmer; simmer uncovered, skimming off fat and impurities now and then, for 12 hours. Add water as needed to maintain the level of liquid in the pot.
Strain stock; cool rapidly in a large bowl placed in an ice bath. Refrigerate or freeze.