Cover and cook on low 8-10 hours.
Before serving remove chicken breasts and shredded into bite-size pieces, return to soup.
Ladle soup in bowl - chips can be placed in the bottom of the bowls first or sprinkled on top with cheese and sour cream. If you want you can cook the chicken first, cut it up in bite-size pieces and add to the soup if you need to shorten the cooking time.
(If I cannot find the Mexican stewed tomatoes, I use Rotel tomatoes or the chili ready chopped/diced tomatoes.)