Preheat oven to 350°F (175°C). Grease a 9x13 inch baking dish.
In a large bowl, combine melted butter, creamed corn, drained whole kernel corn, sour cream, and Jiffy corn muffin mix. Mix well.
Pour the mixture into the prepared baking dish. Sprinkle with shredded cheddar cheese (if using).
Bake for 45 minutes, or until golden brown and set.
Let cool slightly before serving.
Notes
This casserole can be prepared ahead of time and refrigerated until ready to bake. Add a pinch of sugar for a sweeter casserole. Can be topped with a layer of crumbled bacon or jalapenos for added flavor.