Directions

1. Preheat oven to 375 degrees. Line a baking sheet with parchment paper.
2. Whisk together flours, granulated sugar, baking powder, and salt in a large bowl. Cut in butter with a pastry cutter, or rub in with your fingers, until mixture has the texture of coarse meal. Stir in blueberries.
3. Whisk together buttermilk, 1 egg, and the vanilla. Drizzle over flour mixture, and stir lightly with a fork until dough comes together but a small amount of flour remains in bowl.
4. Turn out dough onto a work surface, and gently knead dough once or twice just to incorporate flour. Pat dough into a 1-inch-thick round. Cut into 12 wedges. Transfer to prepared baking sheet. Brush with egg wash, and sprinkle with sanding sugar. Bake until golden brown and cooked through, about 22 minutes. Transfer scones to wire racks to cool. Scones are best served immediately but can be frozen for up to 1 month. Thaw, and reheat in a 350-degree oven for 10 minutes.