Place a 9-inch cast-iron skillet in a 450° oven 5 minutes or until hot.
Combine first 6 ingredients in a large bowl; make a well in center of mixture. Combine buttermilk and next 4 ingredients; add to dry ingredients, stirring just until moistened.
Coat hot skillet with cooking spray; immediately pour batter into hot skillet. Bake at 450° for 20 minutes or until golden. Cut into 10 wedges.