Preheat your oven to 350°F (175°C) and lightly grease a 9x13-inch baking dish with cooking spray or butter.
In a large mixing bowl, combine the drained whole kernel corn and creamed corn, stirring until well mixed.
Add the dry cornbread mix to the corn mixture and stir until just combined.
Mix in the sour cream and melted butter until incorporated.
Add the beaten eggs and stir until everything is well combined. Season with salt and pepper if desired.
Pour the mixture into the prepared baking dish, smoothing the top with a spatula.
Bake in the preheated oven for 45-50 minutes, or until the top is golden brown and the center is set.
Allow the casserole to cool for 5-10 minutes before serving.