01 - Set the oven to 400°F and line a baking sheet with parchment paper.
02 - In a large bowl, whisk together flour, sugar, baking powder, baking soda, salt, and lemon zest.
03 - Add cold cubed butter to the dry mixture and use a pastry cutter or fingertips to blend until the texture resembles coarse crumbs with some pea-sized pieces.
04 - In a separate bowl, whisk cold heavy cream, egg, vanilla extract, and lemon juice until combined.
05 - Pour the wet mixture into the dry ingredients and stir gently until just combined, avoiding overmixing.
06 - Carefully fold fresh or frozen blueberries into the dough.
07 - Turn dough onto a lightly floured surface and pat into a 7-inch diameter round about 1 inch thick.
08 - Slice the dough into 8 equal wedges and arrange them on the prepared baking sheet, leaving space between each piece.
09 - Lightly brush the tops of the wedges with heavy cream.
10 - Bake for 16 to 18 minutes until the scones are golden and fully cooked. Cool on a wire rack.
11 - Whisk powdered sugar, lemon juice, and lemon zest until smooth and slightly runny. Drizzle over cooled scones.