Preheat oven to 350 degrees and spray a 3-quart baking dish with non-stick cooking spray. Set aside.
In a large pan, over medium heat, add in butter and oil.
Once butter is melted, add chicken and onion. Sprinkle with seasonings, stir, and cook until chicken is no longer pink and onions are tender.
Pour in diced tomatoes, enchilada sauce, black beans, corn, green chiles, and cooked rice. Stir to combine.
Spoon mixture into prepared baking dish and cover with shredded cheese.
Bake for 10-15 minutes or until cheese is completely melted and bubbly.
Remove from oven, and top with cilantro and green onions before serving, if desired.