Place the chicken breasts at the bottom of the crockpot.
In a bowl, combine the enchilada sauce, black beans, corn, salsa, onion, cumin, chili powder, salt, and pepper. Mix well.
Pour the mixture over the chicken in the crockpot.
Cover and cook on low for about 6 hours or until the chicken is cooked through and easily shreds with a fork.
Once cooked, shred the chicken directly in the crockpot using two forks and mix it with the sauce.
Layer half of the corn or flour tortillas torn into pieces on top of the chicken mixture.
Sprinkle half of the shredded cheese on top of the tortillas.
Add the remaining chicken mixture on top and finish with the rest of the tortillas and shredded cheese.
Cover again and cook on low for an additional 30 minutes until the cheese is melted and bubbly.
Serve hot, garnished with optional toppings such as sour cream, avocado, and cilantro.