Position a rack in the upper third of the oven. Preheat the oven to 450 degrees F. Thoroughly coat with nonstick spray a heavy 9-inch skillet, preferably cast-iron, or less desirably, an 8 X 8-inch glass baking pan.
In a large bowl whisk together all dry ingredients.
In a separate bowl whisk eggs until foamy, then whisk in the buttermilk.
Add the wet ingredients to the dry ingredients and whisk just until blended. Pour the batter into the skillet or pan.
Bake until the top is browned and the center feels firm when pressed, 20 to 25 minutes. Serve immediately from the pan, cut in wedges or squares.