Combine flour, baking powder, baking soda and salt in the bowl of a large food processor. Pulse twice to evenly distribute the dry ingredients. Scatter the diced butter over the top of the flour mixture and pulse 4 to 5 times or until the mixture resembles a course meal.
Add the cold buttermilk and pulse until the mixture just begins to come together. Scrape the dough onto a lightly floured surface. With your hands, pat the dough into a 10 by 12 inch rectangle about 3/4 inch think. Use a 3 inch round cutter to make 8 biscuits.