Heat oven to 400°F.
Combine flour, cornmeal, sugar, baking powder, baking soda and salt in bowl. Stir in buttermilk, 1/3 cup melted butter and eggs just until mixture is moistened.
Melt 1 tablespoon butter in heavy cast iron or oven-proof 10-inch skillet. Pour batter immediately into pan. Bake 15-20 minutes or until toothpick inserted in center comes out clean. Serve warm.
*Substitute 1 tablespoon vinegar or lemon juice and enough milk to equal 1 cup. Let stand 5 minutes.
If you do not have a cast iron skillet or oven-proof skillet, use an 8- or 9-inch baking pan.