Preheat the oven to 400°F, and grease an 8-inch square pan with nonstick cooking spray.

Combine flour, cornmeal, sugar, baking powder, baking soda, and salt in a large bowl.

In a seperate medium-sized bowl, combine the egg, sour cream, milk, and butter.

Fold the egg mixture into the flour mixture until just moistened, and pour it into the prepared baking dish.

Bake in preheated oven until a toothpick inserted comes out clean, 20-25 minutes. Serve warm and enjoy!