In a large bowl, stir together the 2 cans of corn, corn muffin mix, sour cream, and melted butter. Pour into a greased 9 by 13-inch casserole dish. Bake for 45 minutes, or until golden brown. Remove from oven and top with Cheddar. Return to oven for 5 to 10 minutes, or until cheese is melted. Let stand for at least 5 minutes and then serve warm.