In a large stockpot, at least 8 quarts, place chicken carcasses in then put everything else around the chicken carcasses.
Fill the stockpot with water until the chicken carcasses are covered. Bring to a boil then reduce to an extremely gentle simmer (barely any bubbles) and let cook for 5 hours, uncovered. Stir occasionally.
After 5 hours, remove from heat. Let cool for 1 hour.
After 1 hour, remove the bones, as much as you can then place a large strainer over a large bowl and carefully pour contents of stockpot into the strainer.
Discard contents of the strainer then use a funnel and pour liquid into mason jars. Let sit at room temperature for a few hours then put in the fridge.
Read blog post for directions on freezing and also how long to keep in the fridge.
You don't have to have the bouquet garni that I got from France. It was dried herbs; you can make your own with fresh by tying together fresh thyme, sage, and bay leaves.