Preheat oven to 400 degrees. Line a large baking sheet a silicone baking mat or with parchment paper, set aside.
In a large bowl, whisk the flour, sugar, baking powder, salt, and lemon zest.
Grate the frozen butter using a box grater. (can also use a food processor)
Toss the grated butter into the flour mixture and combine it with a a fork, or your fingers until the mixture resembles large crumbs. Set aside.
In a small bowl, whisk the cream, egg, and vanilla together.
Drizzle over the flour mixture and then lightly toss the mixture together using a spoon or spatula until everything is just moistened.
Gently fold in the blueberries.
The dough will be a little sticky, this is okay. Work the dough into a ball with floured hands as best you can and transfer to a floured surface.
Press into a neat 8-inch circle and cut into 8 equal wedges with a sharp knife.
Place scones at least 2 inches apart on the prepared baking sheet.
Bake for 20-25 minutes or until lightly golden and cooked through.
Remove from the oven and allow to cool for a few minutes.
To make the glaze, mix together the powdered sugar and 2 tablespoons lemon juice together until smooth. Add another Tablespoon of lemon juice to thin out, if need be.
Drizzle glaze over scones right before serving.