Place 3 boneless skinless chicken breasts into the crockpot.
Add 1 can (10 ounces) diced tomatoes with green chilis, 1 tablespoon taco seasoning, ½ chopped onion, 3 cans white beans with the liquid included, and 2 cups chicken broth to the crockpot.
Stir the ingredients gently to combine.
Cover and cook on low for 6–8 hours or on high for 3–4 hours.
Once the chicken is fully cooked, remove the chicken breasts from the crockpot and shred them with two forks.
Return the shredded chicken to the crockpot and stir well.
Serve topped with 1 cup sour cream, 1 bunch chopped cilantro, 1 diced avocado, 1 sliced jalapeño, and 1 cup shredded Monterey Jack cheese if desired.