Prepare the chicken by placing the two boneless, skinless chicken breasts at the bottom of the crockpot.
Chop the vegetables: dice one medium onion and mince two cloves of garlic.
Combine everything in the crockpot: add the drained black beans, corn, and diced tomatoes with green chilies on top of the chicken, then sprinkle the chopped onion and minced garlic.
Pour one cup of chicken broth over the mixture, sprinkle in the spices, and stir gently to combine. Cover the crockpot and set it to cook on low for 6-8 hours or on high for 3-4 hours.
Once the cooking time is up, remove the chicken breasts, shred them, and return to the crockpot, stirring everything together.
Serve the soup hot, topped with crushed tortilla chips, shredded cheddar cheese, sour cream, diced avocado, and fresh cilantro.