01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - In a large bowl, whisk together flour, sugar, baking powder, salt, and lemon zest.
03 - Add cold cubed butter to the dry mixture. Cut in with a pastry cutter or fingertips until it resembles coarse crumbs.
04 - Whisk cream, egg, and vanilla extract in a small bowl. Pour over dry ingredients and gently combine just until moistened.
05 - Carefully fold in blueberries, avoiding overmixing to retain scone tenderness.
06 - Turn dough onto a lightly floured surface and pat into a 1-inch thick circle.
07 - Cut the dough into 8 wedges and place them spaced apart on the prepared baking sheet.
08 - Lightly brush the scone tops with additional heavy cream to promote browning.
09 - Bake for 18 to 22 minutes until golden brown and cooked through. Cool on a wire rack.
10 - Whisk confectioners sugar, milk or cream, and vanilla extract until smooth. Drizzle over cooled scones.