Preheat oven to 400°F and grease an 8-inch square casserole dish.
In a large bowl, whisk together the cornmeal, flour, sugar, baking powder, and salt.
Make a well in the center of the bowl of dry ingredients and add in the melted butter, milk, and egg. Stir well, starting from the middle of the bowl and working your way outwards.
When everything is combined and no dry spots remain, pour the batter into your prepared pan.
Bake for 20-25 minutes until the top is slightly browned and the edges pull away from the casserole dish. You can also insert a toothpick and check that it comes out clean, with just a few crumbs.
Notes
Note: Nutrition information is an estimate only. Your actual values may vary depending on exact ingredients and amounts used.