1Pre-heat the oven to 450 degrees. Pulse the flours, baking powder, sugar, baking soda and salt together in a food processor to combine. Scatter the butter evenly over the top and pulse to combine, about 12 pulses.
2Transfer the mixture to a large bowl. Stir in the buttermilk with a rubber spatula until the mixture forms a soft, slightly sticky ball.
3Turn the dough out onto a lightly floured surface and quickly form into a rough ball. Do not overmix. Use a sharp knife to divide the dough into 12 even pieces. Quickly and gently shape each piece into a rough ball and place on an ungreased baking sheet. (The baking sheet can be wrapped in plastic wrap and refrigerated for up to 2 hours.) Bake until the biscuit tops are light brown, 10 to 12 minutes.