Leftover chicken carcass (with no wings, see below)
1.5 liter water/broth
4 chopped carrots
4 chopped celery
1 chopped onion
3 bay leaves
Salt & pepper
Place all ingredients in a slow cooker on low for about 7 hours or high for about 3 hours. De-bone the chicken and remove bay leaves. Reheat.
De-boning the Chicken
Depending on the the particular method, the consistency of the carcass, and the desired purity of the product; a great deal of suffering can be hid behind the innocent phrase "de-bone the chicken". Based on several attempts, this is what I believe to generally be the best strategy:
Turn the slow cooker off.
Wash your hands.
Get a large bowl and transfer the solid parts of the soup into the bowl with a slotted spoon. 1
Preferably by hand, carefully return the vegetables and meat back to the slow cooker, separating and discarding the bay leaves, bones, cartilage, and other undesirable parts.
The meat around spine can be particularly problematic, and you may want to avoid it altogether and just discard it.
The wings are really no good at all. They are basically little tiny bones with skin hanging off of them. It's highly recommended to lop them off or eat them beforehand.
It can be a little difficult to differentiate the cartilage from the onion.
Turn the heat back on for a while to sterilize the soup.
I don't have a slotted spoon, but a colander on top of a large bowl works too. In this case, excess liquid goes into the bowl and can just be poured back into the slow cooker.