To a 6-quart stockpot add: cut up chicken backs, necks, and wings; 2 carrots, roughly chopped; 2 stalks of celery, roughly chopped; 2 cloves of garlic; a medium onion, cut into quarters; 5 sprigs of parsely; 5 sprigs of thyme; and 2 bay leaves.
Add enough water to cover the ingredients and slowly bring to a simmer over medium heat.
Occasionaly skim the surface during the first hour of simmering.
Continue to simmer for an additional 3 hours.
Remove the stock from the heat, and use tongs or a slotted spoon to remove the larger pieces of bones and vegetables. Discard these pieces.
Pour the remaining broth through a strainer into a large bowl and discard the solids.
Cool stock; cover and refrigerate overnight.
The remaining fat in the stock will rise to the top and congeal, making for easy removal with a slotted spoon.
Use the stock within 3 days, or keep frozen for up to 3 months.