01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - In a large bowl, whisk together all-purpose flour, whole wheat flour, sugar, baking soda, baking powder, and salt until well blended.
03 - Add cold butter cubes to the flour mixture. Using a pastry cutter or your fingertips, work the butter into the flour until the mixture resembles coarse crumbs with some pea-sized pieces remaining.
04 - Stir in the dried currants until evenly distributed throughout the flour mixture.
05 - In a separate bowl, whisk together cold buttermilk and egg until fully combined.
06 - Pour the buttermilk mixture over the dry ingredients. Stir gently with a fork until just combined and a shaggy dough forms. Do not overmix.
07 - Turn the dough out onto a lightly floured surface. Pat gently into a 1-inch thick circle. Cut into 8 wedges and transfer to the prepared baking sheet, spacing them evenly apart.
08 - Optionally sprinkle tops with demerara or turbinado sugar. Bake for 18-20 minutes until golden brown and a toothpick inserted into the center comes out clean.
09 - Cool scones slightly on a wire rack. Serve warm or at room temperature with butter and jam if desired.