Add the potatoes, onion, carrot, celery, ham, Kosher salt, pepper chicken broth to your slow cooker and cook on low 7-8 hours, or high 4-5 hours.Using a potato masher, mash about â…“ of the potatoes (don't worry the ham won't really mash that much)Add the flour, milk and sour cream and stir everything together.Cover and cook on high for an additional 15 minutes.