Preheat the oven to 400°F. In a 9×13 inch baking dish, combine the onion, bell pepper, uncooked rice, fajita seasoning, and cayenne (if using) and stir well to mix.
In a separate bowl or measuring cup, whisk together the chicken broth, green chiles, tomato paste, and olive oil until fully combined.
Pour the broth mixture into the baking dish and stir to combine it with the rice mixture.
Next, add the shredded chicken, black beans, and corn to the baking dish, stirring again until everything is well mixed.
Cover the baking dish with aluminum foil and place it in the oven to bake for 65-70 minutes, or until all the liquid has been absorbed.
When finished, remove the baking dish from the oven, take off the aluminum foil, and sprinkle the grated cheese evenly over the top.
Return the baking dish to the oven for an additional 5-10 minutes, or until the cheese has melted and turned slightly golden.
Once done, take it out of the oven and let it cool for 5-10 minutes before serving, optionally garnishing with fresh cilantro, green onion, salsa, and avocado.