1½ cups all-purpose flour
½ cup cake flour (not self-rising)
3 tablespoons granulated sugar
2½ teaspoons baking powder
¾ teaspoon salt
4 ounces (1 stick) cold unsalted butter, cut into small pieces
1 cup (½ pint) blueberries
½ cup buttermilk
1 large egg, plus 1 large egg lightly beaten for egg wash
½ teaspoon vanilla extract
Sanding sugar, for sprinkling
1. Preheat oven to 375 degrees F. Line a baking sheet with parchment.
2. Whisk together flours, sugar, baking powder and salt in a large bowl. Cut in butter with a pastry blender or rub in with your fingers, until the 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 the 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 rack to cool.
Serving & storing: The 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.