Preparation:
Line rimless baking sheet with parchment paper, or grease; set aside.
In bowl, whisk flour, sugar, baking powder, baking soda and salt. Using pastry blender or 2 knives, cut in butter until in coarse crumbs. In small bowl, whisk buttermilk with egg; add to flour mixture and stir with fork to make soft dough.
With lightly floured hands, press dough into ball. On lightly floured surface, knead gently 10 times. Pat into 3/4-inch (2 cm) thick round. Using 2-1/2-inch (6 cm) floured round cutter, cut out rounds. Place on prepared baking sheet.
Bake in centre of 400°F (200°C) oven until golden, 12 to 15 minutes. (Make-ahead: Let cool. Store in airtight container for up to 1 day or wrap individually in plastic wrap and freeze in airtight container for up to 2 weeks.)
