Rinse the wild rice and place in the crock pot with the chicken, onion, carrot, celery, broth, sage, thyme, rosemary, salt, and pepper. Cook on high for 3 to 4 hours or low for 6 to 8 hours.
Remove the chicken and shred using a fork. Return the chicken to crock pot along with the Greek yogurt. Stir until the soup is smooth.
If the soup needs thickening, combine the optional cornstarch and cold water. Stir until smooth and then gradually add to the soup until desired consistency is reached.
Ladle into serving bowls and top with parsley. Serve and enjoy!