Preheat the oven to 425°. Warm two 9-inch cast-iron skillets over moderate heat. Add 1 1/2 tablespoons of the oil to each and heat.
Meanwhile, in a bowl, sift the flour with the sugar, baking powder and salt. Stir in the cornmeal. Add the milk and eggs and stir lightly. Add the melted butter and stir just until blended. Scrape the batter into the hot skillets; the oil should bubble. Bake for about 18 minutes, or until the center springs back when gently pressed. Transfer to a rack to cool. Serve warm.