1. In a food processor, combine the flour, sugar, baking powder, baking soda, and salt, pulsing once or twice with an on-and-off motion. Add the butter and process, pulsing, until the mixture is crumbly. Drizzle most but not all of the buttermilk over the dry mixture; pulse to combine, without overworking the dough. The dough should hold together and be moi