01 - Lightly grease the interior of a 6-quart slow cooker with cooking spray or oil.
02 - Place chicken breasts at the bottom of the cooker. Sprinkle evenly with cumin, chili powder, garlic powder, salt, and pepper.
03 - Layer the diced onion, red bell pepper, frozen corn, and black beans over the seasoned chicken.
04 - Pour 1 cup of enchilada sauce over the vegetable and bean mixture.
05 - Arrange half of the quartered tortilla pieces over the sauce. Top with 1 cup of shredded Mexican cheese blend.
06 - Repeat layering with remaining enchilada sauce, tortilla pieces, and remaining cheese.
07 - Cover and cook on low setting for 4 hours, or until chicken is fully cooked and tender.
08 - Twenty minutes before serving, shred chicken directly in the cooker using two forks. Mix thoroughly to combine all ingredients and let sit covered to meld flavors.
09 - Serve hot, garnished with chopped fresh cilantro, sliced green onions, and sour cream if desired.