Preheat and prepare. Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish with butter or non-stick cooking spray and set aside.
Mix the rice and sauce. In a large mixing bowl, combine the condensed cream of chicken soup, chicken broth, sour cream, garlic powder, onion powder, salt, black pepper, and paprika. Stir until smooth and fully combined. Add the uncooked rice and mix well to coat.
Add the chicken and vegetables. Fold in the shredded chicken and frozen vegetables. Stir until everything is evenly distributed throughout the mixture.
Transfer to baking dish. Pour the mixture into the prepared 9x13-inch baking dish and spread it out into an even layer using a spatula or the back of a spoon.
Add the first layer of cheese. Sprinkle 1 cup of the shredded cheddar cheese evenly over the top of the casserole. Reserve the remaining 1 cup for later.
Cover and bake. Cover the baking dish tightly with aluminum foil — make sure the seal is snug on all sides to trap the steam. Bake covered for 45 minutes.
Add remaining cheese and finish baking. Remove the foil carefully. Sprinkle the remaining 1 cup of cheddar cheese over the top. Return the dish to the oven uncovered and bake for an additional 15–20 minutes, until the cheese is melted, bubbly, and lightly golden and the rice is fully cooked.
Rest before serving. Remove the casserole from the oven and let it rest uncovered for 10 minutes before scooping and serving. This allows the sauce to thicken slightly and the rice to finish absorbing any remaining liquid.