In medium bowl, stir together flour, 2 tablespoons granulated sugar, the baking powder and salt. Cut in butter, using pastry blender or fork, until mixture looks like coarse crumbs. Stir in buttermilk until dough comes together. Knead 5 to 10 times or until dough is smooth. Shape dough into flattened round; wrap in plastic wrap. Refrigerate about 45 minutes or until dough is firm and cold.