Spray a 2-quart glass baking dish with cooking spray, then set it aside.
In a mixing bowl, stir the shredded chicken, cilantro, black beans, and green chiles together until well mixed. (Check out the link below to learn the quickest and easiest way to shred chicken!)
Spread 2 tablespoons of the enchilada sauce in the bottom of the baking dish. Place 4 tortillas on top of the sauce, overlapping as necessary. (I think it’s much easier to layer the tortillas when they’re cut in half, so that’s how I did it!)
Spoon half of the chicken mixture over the top of the tortillas, then sprinkle with 1/2 cup of the cheese.
Spread half of the sour cream on top of the cheese, and then half of the remaining enchilada sauce as well. Repeat the process by layering the remaining tortillas, chicken mixture, 1/2 cup of cheese, the sour cream, and remaining enchilada sauce.
Cover the baking dish with tin foil, and bake at 375° for 30-35 minutes or until heated through.
Remove the tin foil from the dish, sprinkle with the remaining cheese (and a few dollops of sour cream, if desired) and bake uncovered another 5 minutes. Remove from the oven and let stand for 10 minutes before serving.