With the rack in the middle position, preheat the oven to 400 °F (200 °C). Line a cookie sheet with parchment paper.
In a food processor, combine the flour, sugar, baking powder and salt. Add the butter and pulse until the butter pieces are pea-sized. Add the buttermilk and pulse just long enough to moisten the flour. Transfer to a bowl and fold in the cranberries. Do not overmix.
On a floured surface, flatten the dough with your hands or roll out to about 3/4 inch (2 cm) thick. Using a 2-inch (5 cm) roud cookie cutter, cut the dough into rounds. Arrange the rounds on the baking sheet, leaving space between each one.
Brush with buttermilk and sprinkle with sugar. Bake until golden brown, 15 to 20 minutes. Let cool on a rack.
Serve with Honey-Orange Butter (see recipe). You can freeze the scones.