Preheat your oven to 400°F (200°C).

In a large mixing bowl, combine finely diced onion, red bell pepper, parboiled long-grain brown rice, fajita seasoning, and optional cayenne pepper. Stir until well-mixed, then layer evenly in the bottom of your baking dish.

In a separate bowl, whisk together reduced sodium chicken broth, mild green chiles, tomato paste, and olive oil until well-blended. Pour this mixture evenly over the rice layer in the baking dish.

Gently fold in the shredded chicken, black beans, and frozen corn kernels into the baking dish, ensuring everything is combined evenly.

Cover the baking dish tightly with aluminum foil and bake for 65-70 minutes. The dish is ready when the liquid is absorbed and the rice is tender.

Once fully baked, remove the foil and sprinkle shredded Monterey Jack cheese generously over the top. Return to the oven and bake for an additional 5-10 minutes until the cheese is melted and lightly golden.

Let it cool for 5-10 minutes, then garnish with fresh cilantro, green onion, or avocado before serving.