Heat oven to 350°F (175°C) and lightly grease a 9×13 baking dish.
2. Mix Filling
In a large bowl, combine shredded chicken, corn, black beans, diced tomatoes with chilies, rice (if using), sour cream, salsa, taco seasoning, cilantro, and 1 cup cheese.
3. Assemble
Spread mixture evenly into the prepared baking dish.
Sprinkle the remaining 1 cup of cheese on top.
4. Bake
Bake uncovered for 25–30 minutes, until hot and bubbly and cheese is melted.
5. Serve
Top with crushed tortilla chips, avocado slices, jalapeños, or extra cilantro if desired.