Start by dicing the chicken breasts into bite-sized pieces. Rinse and drain the beans of your choice, and chop any optional vegetables, like bell peppers or zucchini. Set everything aside in separate bowls.

In the bottom of your slow cooker, lay down a layer of tortillas, overlapping them slightly. Follow with half of the chopped chicken, then drizzle half the enchilada sauce over the top. Sprinkle a generous amount of cheese, and then add the beans, followed by any vegetables. Repeat this layering process with the remaining ingredients.

Cover your slow cooker with the lid and set it to cook on low for about 5 hours. Check the chicken for doneness; it should be fully cooked when measured with a meat thermometer, reaching an internal temperature of 165°F.

For an optional finishing touch, preheat an air fryer to 400°F and transfer the casserole to the air fryer basket. Crisp the top for about 5-10 minutes.

Once ready to serve, scoop portions onto plates. Garnish with freshly chopped cilantro and a dollop of sour cream.