Place chicken breasts, wild rice, onion, carrots, celery, chicken broth, water, garlic powder, thyme, parsley, salt, and pepper into the crockpot. Stir to combine.
Cover and cook on low for 6-7 hours or high for 3-4 hours, until the chicken is cooked through and the rice is tender.
Once cooked, remove the chicken, shred it with two forks, and return it to the crockpot.
In a small saucepan, melt the butter over medium heat. Add the flour and whisk for 1-2 minutes to make a roux.
Gradually whisk in the heavy cream, stirring until the mixture thickens. Add this creamy mixture to the soup in the crockpot and stir well.
Let the soup cook for another 15-20 minutes on high to blend the flavors and thicken further.
Serve hot, garnished with fresh parsley if desired. Enjoy with crusty bread or crackers!