In a large bowl, combine the first five ingredients. Add cheeses.
In a small bowl, combine buttermilk and oil. Stir into dry ingredients just until moistened. Drop by 1/4 cupfuls 2 in. apart onto a greased baking sheet. Sprinkle with additional Parmesan cheese if desired.
Bake at 450° for 10-12 minutes or until golden brown. Serve warm.