Slow Cooker Cream of Chicken and Rice Soup

1/2 cup long grain brown rice this is not the quick type of rice
3 carrots peeled and sliced
1 potato large, cut into 1 inch cubes
1 stalk celery diced
1 yellow onion or sweet onion, diced
2 garlic cloves minced
1/2 teaspoon black pepper
1/4 teaspoon crushed red pepper flakes
1/2 teaspoon kosher or sea salt more or less to taste
2 fresh sprigs thyme stems removed
1 pound boneless and skinless chicken breast about two breast filets, cut into 1 inch pieces
4 cups chicken broth recommend bone broth
1 cup milk I used 1%, skim is not recommended for this recipe
1 tablespoon cornstarch

Add all ingredients, except milk and cornstarch, to the slow cooker and stir to combine. Cover and cook on low 6 to 8 hours, or until chicken is cooked and carrots and rice are tender.
Before turning off the slow cooker, add the milk and stir to combine. Cook about an additional 10 minutes.
If a thicker soup is preferred: whisk together the milk with 1 tablespoon cornstarch. Add the milk mixture and stir. Cover, and continue cooking until soup has thickened, about 10 minutes.

If you prefer a more subtle onion flavor, saute diced onion in 1 tablespoon olive oil until tender, about 5 minutes. Add to slow cooker.