Whether its a chicken you baked from scratch, or one you brought home from the deli, you can give those chicken bones a new life as soup stock.
1) Begin with the bones of a chicken, or a bag of beef bones (If you are doing beef stock. Even if you don't buy whole chickens, you can save the bones from your wings and legs in a bag in the freezer, until you have a sufficient amount (about equal to the size of a chicken carcass).
2) Put the bones in a large stock pot, completely covered by water, add a few couple tablespoons of apple cider vinegar (this will leach all the good minerals out of the bones)
3) Add vegetables, as vegetables start to turn in my fridge, I throw them into a bag in my freezer. I also throw all the scraps from chopping into the freezer too. I usually add: a large onion (chopped in quarters, leave the peel on for a beautiful yellow color in your stock), 2-3 carrots and 2-3 celery sticks (chopped in large pieces).
3) Bring to a boil, and remove the scum that rises to the top.
4) Reduce heat, cover and simmer for 6 to 24 hours (the longer, the better, as this will allow the gelatin to be more fully released from the bones, and results in a more flavorful broth). I usually throw mine into a crockpot overnight for about 24 hours. You can add fresh parsley or thyme to your stock in the last 10-15 minutes. Also, add a bit of salt, to bring out the flavors.
5) Pour through a strainer and set broth aside to cool Set aside bones and remove all meat for future soups, casseroles, etc. When broth is cool, remove layer of congealed fat from the top and discard.
6) Put broth in containers