Preheat the oven to 425°. Whisk together first 6 ingredients (through soda) in a large bowl. Combine buttermilk, butter, and egg in a small bowl; stir with a whisk. Add buttermilk mixture to cornmeal mixture, stirring until moist. Pour into a 9-inch baking pan coated with cooking spray. Bake 27 minutes, or until a wooden pick inserted into center comes out clean. Remove from pan, and cool on a wire rack.
Tear cornbread into small chunks; place on a baking sheet. Bake at 425° for 15 minutes, or until lightly browned and toasted.