Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish with olive oil or cooking spray.
In a large mixing bowl, combine the cooked rice, cooked chicken, cream of chicken soup, frozen mixed vegetables, milk, garlic powder, onion powder, black pepper, salt, and paprika. Mix until well combined.
Pour the mixture into the prepared baking dish and spread it evenly.
Sprinkle the shredded cheddar cheese on top of the casserole.
Cover the dish with aluminum foil and bake in the preheated oven for 25 minutes.
Remove the foil and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly.
Allow the casserole to cool for a few minutes before serving.