Spray a large slow cooker with non-stick cooking spray.
Add the first 15 ingredients to the slow cooker (from the chicken through the salt) and let cook on low for 6-8 hours or until chicken is fully cooked.
Remove chicken from slow cooker and add in cheese, sour, cream, and milk (as much or as little as you prefer).
Shred the chicken with two forks and return to slow cooker.
Let soup cook on low for 15-20 minutes or until cheese is melted and soup has reached desired thickness.
Serve topped with sour cream, shredded cheese, and tortilla strips if desired.
