Place oil in a 10-inch cast-iron skillet, tilting pan to coat bottom evenly; heat in a 375° oven 10 minutes.
Combine flour, cornmeal, baking powder, and salt in a bowl. Whisk together milk and egg; add to flour mixture, stirring just until dry ingredients are moistened.
Pour hot oil from skillet into batter; stir until blended. Pour batter into skillet.
Bake at 375° for 20 minutes or until done. Remove from skillet.