Preheat your oven to 400°F (200°C).

Place your cast iron skillet in the oven while it preheats.

In a mixing bowl, whisk together the cornmeal, flour, sugar, baking powder, and salt.

In another bowl, combine the buttermilk, eggs, and melted butter. Whisk until well blended.

Pour the wet ingredients into the dry ingredients and stir until just combined.

Remove the hot skillet from the oven and pour in the batter.

Bake for 20 minutes or until the top is golden brown and a toothpick inserted in the center comes out clean.

Let the cornbread cool in the skillet for a few minutes, then slice and serve warm.