Preheat oven to 425°F (220°C).

In a large bowl, combine flour, cornmeal, baking powder, sugar, and salt.

In a separate 1-quart measuring cup, pour in the buttermilk.

Add eggs to the buttermilk and beat with a fork.

Add the melted butter and baking soda to the buttermilk mixture.

Place a tablespoon of butter in a 9-inch square pan or No. 10 cast-iron skillet.

Put the pan in the oven to melt the butter.

Combine the dry ingredients with the buttermilk-egg mixture until just blended.

The mixture should be thin enough to pour.

If needed, add more buttermilk to achieve the desired consistency.

Pour batter into the hot, buttered pan.

Bake for 15 to 20 minutes, or until the cornbread is light golden brown on top.

Serve hot with butter.