Preheat oven to 375F. Spray a 10” cast iron skillet or a bread pan with cooking spray. Place in the oven.
In a large bowl, whisk together the dry ingredients – cornmeal to baking soda. In a second bowl, whisk together the rest of the ingredients. Stir the buttermilk mix into the flour mix, and stir until just combined. Spread into the prepared pan (remove form the oven and handle carefully as it is quite hot!)
Bake until golden brown, about 20 minutes for a cast iron skillet or 25 minutes for a loaf pan. Let cool in the pan 10 minutes before turning out.