Preheat oven to 350°F and grease a 9×9-inch baking dish with nonstick spray. Set aside.
In a large bowl, stir together the chicken, Ro-Tel, rice, 1 1/2 cups of the cheese, sour cream, taco seasoning, milk, corn, and black beans.
Pour mixture into baking dish and top with remaining cheese.
Cover tightly with foil and bake for 20 minutes. Uncover, and cook until cheese is melted and bubbly, 5-10 minutes. Let sit 5 minutes before serving. Enjoy!