01 - Preheat oven to 450°F. Line a baking sheet with parchment paper.
02 - In a large mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, salt, and granulated sugar.
03 - Add the cold, cubed butter to the dry ingredients. Using a pastry cutter or your fingertips, cut the butter into the flour mixture until it resembles coarse crumbs with some pea-sized pieces.
04 - Create a well in the center of the flour mixture and pour in the cold buttermilk. Stir gently with a fork just until the dough comes together; be careful not to overmix.
05 - Turn the dough onto a lightly floured surface. Pat it into a rectangle about 1 inch thick. Fold the dough in half, then pat it out again. Repeat this folding and patting process 2-3 times to enhance flakiness.
06 - Using a 2.5 inch biscuit cutter, cut out individual biscuits. Press straight down to cut, avoiding twisting the cutter. Gather any dough scraps, re-pat them gently, and cut additional biscuits.
07 - Place the cut biscuits, with their sides lightly touching, onto the prepared baking sheet. Lightly brush the tops of the biscuits with a little extra buttermilk.
08 - Bake for 12–15 minutes, or until the tops are golden brown. Remove from the oven and serve warm.