Start by placing the chicken breasts in a large bowl. Sprinkle the cumin, chili powder, garlic powder, salt, and pepper over the chicken. Toss well to coat each piece evenly with the spices.
Begin by spreading a thin layer of enchilada sauce on the bottom of the crockpot. Next, add a layer of tortilla strips to cover the sauce. Place half of the seasoned chicken breasts on top of the tortillas. Then evenly sprinkle half of the black beans, corn, and diced tomatoes over the chicken. Pour about one cup of enchilada sauce over the layer to keep everything moist.
Repeat the layers starting with the remaining tortillas, then the rest of the chicken, beans, corn, tomatoes, and enchilada sauce.
Cover the crockpot with the lid and cook on low for 6–7 hours or on high for 3–4 hours.
Once the cooking time is up, remove the chicken breasts and shred them using two forks. Return the shredded chicken to the crockpot and stir gently to combine with the beans, corn, and tomatoes.
Sprinkle the shredded cheddar and Monterey Jack cheese evenly over the top. Cover and let the cheese melt for 10–15 minutes with the crockpot on warm or low.
Before serving, sprinkle the casserole with fresh chopped cilantro for a pop of color and freshness. Serve hot with your favorite sides or a dollop of sour cream and avocado slices.