Preheat oven to 250C.
Whisk flours, baking powder, and baking soda until well-blended.
Rub in butter with your fingers, until the mixture resembles coarse crumbs.
Pour in buttermilk, and stir lightly until the dough comes together.
Pat dough out onto a floured surface; 3/4 to 1 inch thick. Cut out circles as desired, and place the biscuits onto a baking sheet so that the sides are touching.
Bake at 250C for 8-10mins.