01 - Lightly grease the interior of a 6-quart slow cooker with cooking spray or a thin layer of oil.
02 - Place chicken breasts at the bottom of the slow cooker. Sprinkle evenly with cumin, chili powder, garlic powder, salt, and black pepper, pressing the seasonings gently into the meat.
03 - Layer diced onion, red bell pepper, frozen corn, and drained black beans over the seasoned chicken, distributing evenly.
04 - Pour 1 cup of enchilada sauce over the vegetable mixture, ensuring even coverage.
05 - Arrange half of the quartered tortilla pieces over the sauce and vegetables. Top with 1 cup of shredded Mexican cheese blend.
06 - Add remaining enchilada sauce, followed by remaining tortilla pieces, and finish with the remaining cup of shredded cheese.
07 - Cover and cook on low heat for 4 hours, until chicken is fully cooked and tender, reaching an internal temperature of 165°F.
08 - Twenty minutes before serving, shred the chicken directly in the slow cooker using two forks. Stir thoroughly to incorporate all ingredients, then recover and allow flavors to meld.
09 - Serve hot, garnished generously with fresh cilantro, sliced green onions, and a dollop of sour cream.