Preheat oven to 400 F.
Shred your cooked chicken and set aside.
In a large casserole dish (2 or 3 quart), add chopped onion, rice, cumin, chili powder, oregano and garlic powder. Mix and set aside.
In a medium bowl whisk together the chicken broth, tomato paste and olive oil.
Pour it on top of the onion/rice mixture. next add the cooked shredded chicken, followed by the black beans and corn.
Cover with foil and bake for 35-40 minutes.
Remove from oven and uncover.
Sprinkle cheese on top and cook 5-10 more minutes.
Top with cilantro, green onion, and avocado.