Preheat your oven to 350ºF. This step is essential to ensure your casserole cooks evenly and thoroughly when it's time to bake.
Grab a 9×13-inch baking dish and spray it with nonstick cooking spray. This helps prevent any sticking and makes cleanup a breeze later.
In a large mixing bowl, stir together the cream of chicken soup, sour cream, and chicken stock. Mix until you have a smooth and creamy consistency. This will form the base of your casserole.
Once combined, add in the cooked chicken, uncooked orzo pasta, frozen corn, black beans, Rotel, and taco seasoning. Season with salt and black pepper to taste. Get in there with a spatula and stir everything together until it’s well combined and coated with the creamy mixture.
Now, pour this delicious mixture into your prepared baking dish. Spread it out evenly, ensuring every bite will be packed with flavor.
Next, top the casserole with the remaining shredded cheddar cheese. This is where the magic happens; it melts into a gooey, bubbly topping that everyone will love.
Cover the baking dish with aluminum foil. This helps retain moisture during the first part of baking, ensuring your casserole remains moist and delicious.
Place the dish in the preheated oven and bake for 25 minutes. This allows the flavors to meld and the orzo to begin cooking.
After 25 minutes, carefully remove the foil. Continue baking for an additional 10 to 15 minutes, or until the cheese is melted and bubbly. Keep an eye on it; you want it golden but not burnt!
Once done, take it out of the oven and let it sit for a few minutes before serving. This allows everything to settle, making it easier to serve.