Preheat your oven to 350°F (175°C). This ensures that your casserole cooks evenly and thoroughly.
In a large mixing bowl, combine the cooked chicken, instant rice, cream of chicken soup, sour cream, canned corn, black beans, RO*TEL, chicken broth, and taco seasoning. Stir until well mixed, ensuring all ingredients are evenly distributed.
Pour the mixture into a greased 9x13 inch baking dish. Spread it out evenly with a spatula to ensure even cooking.
Sprinkle the Mexican blend cheese generously on top of the casserole. This will melt beautifully during baking and add that cheesy goodness we all love.
Place the casserole in the preheated oven and bake for 30-35 minutes, or until the cheese is bubbly and the edges are lightly golden.
Once out of the oven, let the casserole cool for a few minutes. Then, top with chopped cilantro, crushed tortilla chips, and serve with sour cream and guacamole on the side for extra flavor.