Combine chicken stock, celery root, onion, garlic and thyme in a large pot. Bring to a boil and then reduce heat to a simmer.
Simmer uncovered for 20-25 minutes, until celery root is soft when pierced with a knife.
Puree soup using an immersion blender (you could do this in a conventional blender but be careful not to burn yourself!). Note: if the stocks of your thyme sprigs are very tough, you might want to remove them before pureeing.
Stir in butter and wine. Let simmer another 3-5 minutes.
Recipe by The Paleo Mom at https://www.thepaleomom.com/recipe-cream-of-celery-root-soup/