When the vegetables are done roasting, dump them into the pot with the chicken.
Add a whole bunch of fresh parsley. Don't bother taking the stems off or chopping it. Just dump it in. Throw in some salt and pepper and a crumbled dried bay leaf. Fill it to within 3" of the top of the pot with water. Bring to a boil.
Skim the foam off the top as the soup starts to boil. Then, reduce the heat to low, cover, and simmer for about two hours.
Remove from heat and pour the soup through a colander. Discard the chicken and veggies.
Then, line the colander with cheesecloth and strain the broth. You'll collect some funky-looking gunk on the cloth, and your broth will be golden and pristine.
Now, let it cool, then package it and store it in the fridge or freezer.