Preheat oven to 400 degrees. Line a baking sheet with parchment paper or a silicone baking mat. Set pan aside. Using a grater, shred the very cold butter into shreds.
In a separate bowl, combine the cream, egg and vanilla. Mix together with a whisk or fork and pour into flour mixture. Gently mix together just until all ingredients are incorporated. Gently fold in the blueberries until just combined. Do your best to not overwork the dough.
Transfer the dough to a lightly floured surface. (Flour your hands to keep the dough from sticking.) Shape into a ball, then press into a disk about 1" in thickness. Cut the disk into 8 slices. A sharp knife or pizza cutter works well.
Transfer the scone triangles to the prepared baking sheet. Bake at 400 degrees for 22-24 minutes or until golden brown. Remove from oven and let cool for 15-20 minutes before glazing.
For glaze: mix together the powdered sugar and lemon juice. Mix until thick, but smooth. Drizzle over the scones. Let set for a few additional minutes. Enjoy!