Preheat the oven to 400 degrees F. Lightly spray a baking pan with nonstick spray (or line with parchment paper).
Mixing with the food processor: Place the flour, sugar, baking powder, baking soda and salt in the bowl of a food processor. Pulse the dry mixture together a few times to blend. Add the butter and continue to pulse until fine crumbs form. Scrape the mixture into a bowl and stir in the buttermilk with a wooden spoon until the dough is mixed together and a little sticky. Mixing by hand: In a large bowl, whisk together the dry ingredients. Add the butter and use a pastry cutter (or use your fingers) to work the butter into the dry mixture and form fine crumbs. Stir in the buttermilk with a wooden spoon until the dough is mixed together and a little sticky.
Turn the dough out onto a floured surface; knead lightly and form into a small round. Roll the dough into a 9x5-inch rectangle (½-inch thick); dust the top of the dough lightly with flour. Fold the dough crosswise into thirds (as if you're folding a piece of paper to slide into an envelope). Re-roll the dough into another 9x5-inch rectangle (½-inch thick). Fold into thirds again; roll into another rectangle. Cut the dough with a 1¾-inch biscuit cutter to form 12 to 14 dough rounds. Gather the scraps and gently pat the dough together again to cut more biscuits.
Place the dough rounds, 1-inch apart, on the prepared baking sheet. Bake for 12 minutes, or until the biscuits are golden brown. Remove the biscuits from the pan; cool 2 minutes on wire racks. Serve warm.
If the dough seems too sticky, sprinkle a little more flour, as needed, and knead it into the dough.