Preheat oven to 450 degrees.
Add flour, sugar, baking powder, and salt to a food processor. Pulse a few times to combine, then add the butter. Pulse again until the mixture is combined - it will resemble sand.
Add in egg, vanilla bean or extract, and 3/4 cup heavy cream, pulse to combine. The dough will be pretty sticky.
Remove blade from food processor, and fold in blueberries and lemon zest with a spatula.
Turn dough out onto a floured surface. Knead lightly - you'll need extra flour for this! Form into a roughly 8-10 inch round. Slice in half, into quarters, then into eighths.
Place scones on a baking sheet lined with parchment paper or a baking Silpat. Bake for 11 minutes, or until golden brown. Transfer to a cooling rack and cool completely before topping with the glaze.