01 - Place the chicken bones into the slow cooker.
02 - Add the roughly chopped carrots, celery, quartered onion, and smashed garlic cloves on top of the bones.
03 - Tuck in the bay leaves, whole peppercorns, fresh parsley, and thyme sprigs among the bones and vegetables.
04 - Pour in the apple cider vinegar and cold water, ensuring all ingredients are fully submerged.
05 - Cover and cook on LOW for 12 to 18 hours, skimming off any foam that rises to the surface as needed.
06 - Carefully strain the finished broth through a fine-mesh sieve or cheesecloth into a large bowl. Discard all spent solids.
07 - Season the strained broth with salt to taste. Allow it to cool, then skim off and discard any solidified fat from the surface if desired.
08 - Transfer the broth to airtight containers or jars. Refrigerate for up to 5 days or freeze for longer storage.