Heat oven to 400°.
Melt one stick of butter in a small bowl in the microwave oven. Set aside.
Combine the dry ingredients in a large bowl and mix thoroughly. (Flour, cornmeal, sugar, baking powder, baking soda, and salt.)
Add the wet ingredients to the flour mixture. (Eggs, buttermilk, and melted butter.) Stir to combine.
Place a 9- to 10-inch cast iron skillet on the stovetop and add the remaining quarter-stick of butter. Heat until the butter is melted and bubbly.
Add the batter to the skillet and place in pre-heated oven.
Bake for 20 to 24 minutes, until the top is golden and a knife inserted in the center comes out clean.