1 cup (5 ounces) all-purpose flour
1 cup (4 ounces) cake flour
2 teaspoons baking powder
½ teaspoon baking soda
1 teaspoon sugar
½ teaspoon salt
8 tablespoons (1 stick) cold unsalted butter, cut into ¼-inch cubes
¾ cup cold buttermilk
1. Adjust an oven rack to the middle position and heat the oven to 450 degrees F.
2. Place the flours, baking powder, baking soda, sugar, and salt in a large bowl or the workbowl of a food processor fitted with the metal blade. Whisk together or process with six 1-second pulses.
3. If making by hand, use two knives, a pastry blender, or your fingertips to quickly cut in the butter until the mixture resembles coarse meal with a few slightly larger butter lumps. If using a food processor, remove the cover and distribute the butter evenly over the dry ingredients. Cover and process with twelve 1-second pulses.
4. If making by hand, stir in the buttermilk with a rubber spatula or fork until the mixture forms a soft, slightly sticky ball. If using a food processor, remove the cover and pour the buttermilk evenly over the dough. Process until the dough gathers into moist clumps, about eight 1-second pulses.
5. Transfer the dough to a lightly floured surface and quickly form into a rough ball. Be careful not to overmix. Pat the dough into a ¾-inch-thick circle. Cut out the dough rounds with a biscuit cutter. Push together the remaining pieces of dough, pat into a ¾-inch-thick, and cut out several more dough rounds. Discard the remaining scraps. Place the biscuits on an ungreased cookie sheet.
6. Bake until the biscuit tops are light brown, 10 to 12 minutes. Serve immediately.
* Note 1: If you don't have cake flour on hand, substitute an extra cup of all-purpose flour and increase the buttermilk by 2 tablespoons.
* Note 2: Once the unbaked biscuits are placed on the cookie sheet, the sheet can be wrapped in plastic and refrigerated for up to 2 hours.