Use chef Mourad Lahlou's chicken stock recipe to make his Classic Steamed Couscous from "Mourad: New Moroccan."
Place backs, necks, bones, and wings in a 16-to-20 quart stock pot; add enough water to cover (about 32 cups). Place a parchment paper round brushed with water in pot directly on surface of water to keep bones submerged. Bring to a simmer over medium heat. Pull pot off to side of burner so that impurities will move to one side.
Meanwhile, line strainer with two layers of dampened cheesecloth set over a bowl. Simmer stock, skimming impurities with a ladle and straining them through prepared strainer (returning strained liquid to pot, for 2 hours, taking care to rinse cheesecloth and strainer in between uses. Occasionally, move bones around in stock pot using tongs, to prevent sticking.
Add carrots, celery, onion, garlic, thyme, bay leaves, and peppercorns to pot. Add more water, if necessary, to cover; simmer until stock has a rich chicken taste, 2 to 3 hours more.
Line a large fine-mesh strainer with two layers of dampened cheesecloth; set strainer over a large storage container or bowl. Ladle stock from pot into strainer, disturbing bones as little as possible to avoid clouding the stock, tilting pot as necessary to get liquid from bottom. Discard bones and vegetables. Let cool to room temperature.
This recipe can be refrigerated for up to 3 days or frozen for up to 3 months.