Combine first 5 ingredients in a bowl; make a well in center of mixture. Combine milk and next 3 ingredients; stir well. Add to dry ingredients, stirring just until moistened.
Place a 9-inch cast-iron skillet in a 450° oven for 5 minutes. Remove from oven; heavily coat skillet with cooking spray, and immediately spoon batter into skillet. Bake at 450° for 27 minutes or until a wooden pick inserted in the center comes out clean.