Preheat oven to 400˚F. Line a baking sheet with parchment paper and set aside.
In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt. Add in the butter pieces; cut in the butter using a pastry blender or a fork to form fine crumbs.
Stir in the buttermilk, egg, and vanilla; mix just until combined. Using a spatula, fold in the blueberries.
Turn out the dough onto the previously prepared baking sheet. Flour your hands and shape the dough into a circle.
Using a sharp knife, cut the circle into 8 wedges. Spray the tops with cooking oil and sprinkle with turbinado sugar, if using.
Bake for 20 to 23 minutes, or until golden on top.
In the meantime, prepare the glaze by combining the powdered sugar, milk, and lemon juice in a mixing bowl; whisk until everything is completely incorporated and no lumps appear. Add more liquid if needed. For a thicker glaze, add more powdered sugar.
Remove the scones from the oven and transfer them to a wire rack.
Set aluminum foil under the wire rack to catch the drippings of the glaze. Drizzle the glaze over the blueberry scones.