Preheat the oven to 350°F. Grease an 8x8-inch baking dish.
In a large bowl, whisk together the corn, creamed corn, sour cream, melted butter, and egg.
Stir in the corn muffin mix.
Transfer the batter to the prepared baking dish and bake in the preheated oven for 50-55 minutes until the top is golden brown.
Let the casserole sit for at least 10 minutes before serving.
