Mix all dry ingredients together. Stir eggs into buttermilk and add to dry mixture. Melt butter inside heavy iron skillet. Coat skillet with butter on all sides. Pour remaining butter from skillet into cornbread batter and mix thoroughly. Pour the cornbread batter into hot skillet and bake in a 375 degree oven. Cook bread until it has a golden brown crust (approximately 25-30 minutes).