01 - Set oven temperature to 400°F and prepare a baking sheet lined with parchment paper.
02 - Whisk together flour, sugar, baking powder, baking soda, salt, and lemon zest in a large bowl.
03 - Incorporate cold butter cubes into dry ingredients using a pastry blender or fingertips until mixture resembles coarse crumbs.
04 - Whisk heavy cream, egg, and vanilla extract together in a separate bowl.
05 - Pour wet mixture into dry ingredients and gently stir until just combined, avoiding overmixing.
06 - Carefully fold blueberries into the dough using a spatula.
07 - Transfer dough onto a lightly floured surface and pat into a 7-inch diameter circle approximately 3/4 inch thick.
08 - Slice dough into 8 equal wedges and place them evenly on the prepared baking sheet.
09 - Lightly brush the tops of scones with heavy cream for a golden finish.
10 - Bake for 18 to 20 minutes until golden brown, then transfer to a wire rack to cool.
11 - Whisk powdered sugar, milk or cream, and vanilla extract until smooth.
12 - Drizzle the vanilla glaze evenly over cooled scones before serving.