Place the chicken breasts at the bottom of the crockpot.
Pour one can of enchilada sauce over the chicken, spreading it evenly.
In a mixing bowl, combine black beans, corn, diced onion, cumin, garlic powder, chili powder, salt, and pepper.
Layer the bean mixture over the chicken in the crockpot.
Add the tortilla strips on top of the bean mixture, then pour the second can of enchilada sauce over everything.
Cover the crockpot and cook on low for 6 hours or on high for 3 hours, until the chicken is cooked through.
About 30 minutes before serving, shred the chicken directly in the crockpot using two forks and stir everything well.
Top with shredded cheese and cover until melted.
Once the cheese is melted, serve hot, and garnish with cilantro, sour cream, or avocado as desired.