Celery Root Soup with Rotisserie Chicken, Kale, and Cremini Mushrooms

This is the “cheater’s version” for a bowlful of nourishment. I’m not quite starting from scratch in making my own chicken stock, but I want the rich flavors just the same. So, the cheater grabs a ready-made rotisserie chicken from the grocery store, quickly pulls the meat off the bones (it usually falls off the bones all by itself), and dumps the bones into a pot with classic vegetables and aromatics for making stock. Walk away and let it simmer (ideally in a slow cooker), and a couple of