Combine first 5 ingredients in a large bowl; make a well in center of mixture. Combine buttermilk and next 3 ingredients; add to cornmeal mixture, stirring just until dry ingredients are moistened.
Spoon batter into a preheated 10-inch cast-iron skillet coated with cooking spray. Bake at 450° for 20 to 25 minutes or until cornbread is lightly browned. Cut into wedges, and remove from skillet immediately.