8 cups low-sodium chicken broth
1 pound boneless, skinless chicken breasts
1 cup wild rice
1 medium onion, diced
3 medium carrots, peeled and chopped
3 medium celery stalks, chopped
1 teaspoon dried thyme
2 bay leaves
1 teaspoon kosher salt
2 tablespoons unsalted butter
2 tablespoons all-purpose flour
1 cup whole milk, at room temperature
Place the broth, chicken, wild rice, onion, carrots, celery, thyme, bay leaves, and salt in a 6-quart or larger slow cooker. Cover and cook on the LOW setting for 7 to 8 hours, or on the HIGH setting for 3 to 4 hours.
Transfer the chicken to a cutting board or large plate, and use 2 forks to shred the meat. Return the chicken to the slow cooker.
Melt the butter in a small saucepan over medium heat. Whisk in the flour until it's completely incorporated. Cook for about 2 minutes, whisking constantly. Gradually whisk in the milk. Bring to a boil, then cook, stirring frequently, until the mixture is smooth and thickened, 3 to 4 minutes. Add and stir into the soup. Serve immediately.