Add all the ingredients into the slow cooker, except for the tortellini, spinach, parmesan and salt and pepper.
Combine, cover and cook on high until the chicken is tender, 3 to 4 hours.
About 30 minutes before serving, remove the chicken breast and shred: place your cooked chicken breast on a plate, separate the chicken meat using two forks. Return shredded chicken to soup (if using pre-cooked chicken skip this step)
Add spinach and tortellini. Stir, cover and cook on high for 30 minutes or until the tortellini are al dente cooked through.