Preheat the oven to 350°F.

In a large bowl, combine 21 ounces cream of chicken soup (two 10.5‑oz cans), 1 cup sour cream, and 3 tablespoons taco seasoning. Stir until smooth.

Pour in 2 cups chicken broth and mix until the mixture is uniform and smooth.

Add 3 cups cooked chicken (chopped or shredded), 2 cups instant rice, 10 ounces ROTEL (undrained), 15.25 ounces canned corn (drained), and 15 ounces canned black beans (drained and rinsed). Stir until all ingredients are evenly distributed.

Pour the mixture into a 9×13-inch baking dish and spread into an even layer.

Evenly sprinkle 1 cup Mexican blend cheese over the top.

Cover the dish tightly with foil or a lid and bake in the preheated oven for 40 minutes.

Remove the foil and bake uncovered for an additional 10–15 minutes, until the sides are bubbly and the casserole is heated through and the cheese is melted.

Let the casserole rest for about 5 minutes, then top with chopped cilantro and crushed tortilla chips. Serve with sour cream and guacamole.