Preheat oven to 350°F (175°C).
In a large bowl, combine the drained sweet corn, creamed corn, sour cream (or Greek yogurt), melted butter, corn muffin mix, sugar, and egg.
Mix until just combined. Be careful not to overmix.
Grease a 8×8 inch baking dish with butter or cooking spray.
Pour the corn mixture into the prepared baking dish and spread evenly.
Bake in the preheated oven for 45-50 minutes, or until golden brown and set. A toothpick inserted into the center should come out clean.
Let it rest for 10 minutes before serving.