Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the shredded chicken, black beans, corn, enchilada sauce, diced tomatoes, chili powder, cumin, salt, and pepper. Mix until well combined.
Pour the chicken mixture into a greased 9x13 inch baking dish, spreading it out evenly.
In another bowl, combine the cornbread mix, milk, and egg. Stir until just combined.
Pour the cornbread batter over the top of the chicken mixture in the baking dish, spreading it evenly.
Sprinkle the shredded cheddar cheese over the cornbread layer.
Bake in the preheated oven for about 35-40 minutes, or until the top is golden brown and a toothpick inserted into the cornbread comes out clean.
If the cheese begins to brown too quickly, you can loosely cover the casserole with aluminum foil halfway through baking.
Allow the casserole to cool for about 5-10 minutes before slicing. Serve warm, garnished with optional toppings as desired.