2-1/2 cups all-purpose flour
2 tablespoons baking powder
1 teaspoon sugar
1 teaspoon salt
1/2 cup (1 stick) cold, unsalted butter, cut into small pieces
1 cup buttermilk
Preheat the oven to 425 degrees F. In the bowl of a food processor, combine the flour, baking powder, sugar and salt and pulse to mix well.
Add the butter and pulse until the mixture resembles a coarse meal. Add the buttermilk and process until the dough comes together in a sticky ball. (If you don't want to use a food processor, you can whisk the dry ingredients together in a large mixing bowl and cut the butter into them with a pastry cutter or two knives. Stir in the buttermilk until a sticky dough forms.)
Turn out the dough onto a floured surface and roll it into 1-inch-thick rectangle. Fold the rectangle in half over itself and roll it out again to a 1-inch-thick rectangle. Repeat about five more times.
Cut the dough with a 2-inch round cutter. Arrange the rounds on a baking sheet and bake in the preheated oven for 10 to 15 minutes, until golden brown.
Serve hot.