- Put the butter in a 10-inch cast-iron skillet and place it in the oven as it heats to 425°F (220°C).
- Whisk the cornmeal, flour, sugar, baking powder, baking soda and salt in a bowl.
- In another bowl, whisk the buttermilk and eggs.
- Carefully take out the hot skillet. Pour most of the melted butter into the buttermilk mixture, leaving a coating in the pan.
- Stir the wet ingredients into the dry until just combined. Pour the batter into the hot skillet. It should sizzle.
- Bake until golden and a toothpick comes out clean, 20 to 25 minutes. Rest 5 minutes, then cut into wedges.