Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish with butter or non-stick spray.
In a large mixing bowl, combine the cornbread mix, whole kernel corn, creamed corn, sour cream, melted butter, eggs, salt, and black pepper. Stir until well incorporated.
Pour the mixture into the prepared baking dish and spread evenly. Sprinkle shredded cheddar cheese on top if using. Bake for 40-45 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean.
Let the casserole cool for 5 minutes before serving. Enjoy this warm, creamy, and fluffy cornbread casserole with your favorite dishes!