Preheat the oven to 375 degrees F.

In large mixing bowl, combine flours, sugar, baking powder, lemon zest and salt. Add butter and use your fingers, pastry cutter or two forks to work butter into dry ingredients into pea-sized pieces.

Add blueberries and stir to combine.

Make well in center of flour mixture and add buttermilk and egg. Beat egg to break it up, then gently fold wet ingredients into dry ingredients until just combined. Be careful not to overmix.

Turn dough out onto lightly floured work surface and knead until it just starts to come together, 3 to 4 times. Shape dough into circle about 1-in. thick.

Slice scones into eight wedges and transfer to baking sheet, leaving couple of inches of space between each piece.

Bake until golden brown, 15 to 20 minutes. Transfer to wire rack to cool.

Meanwhile, make glaze by whisking together powdered sugar, milk and vanilla until smooth and pourable.

When scones are cool, drizzle with glaze.