01 - Place chicken, mushrooms, carrots, celery, onion, garlic, wild rice, thyme, rosemary, bay leaf, salt, and black pepper into the slow cooker.
02 - Pour in the chicken broth and stir everything together until evenly distributed.
03 - Cover and cook on LOW for 6 to 7 hours or on HIGH for 3 to 4 hours, until the chicken is fully cooked and the wild rice is tender.
04 - Transfer the chicken to a plate and shred using two forks, then return the shredded meat to the slow cooker.
05 - Melt butter in a small saucepan over medium heat, then whisk in flour to form a roux and cook for 1 to 2 minutes until lightly golden.
06 - Slowly whisk the heavy cream into the roux, heating until the mixture thickens, then stir it into the slow cooker.
07 - Stir well, cover, and continue cooking on LOW for an additional 20 to 30 minutes until the soup is creamy and heated through.
08 - Remove and discard the bay leaf, taste the soup, and adjust seasoning as needed before serving hot.