Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish with cooking spray or butter.
In a large mixing bowl, combine the whole kernel corn, creamed corn, Jiffy corn muffin mix, sour cream, melted butter, salt, and black pepper. Stir until well combined.
If using, fold in the shredded cheddar cheese until evenly distributed.
Pour the mixture into the prepared baking dish and spread it out evenly.
Bake in the preheated oven for 45-50 minutes, or until the top is golden brown and a toothpick inserted in the center comes out clean.
Allow the casserole to cool for about 10 minutes before serving.