- 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.