Preheat oven to 400º.
Line a cookie sheet pan with parchment paper.
Mix flour, granulated sugar, baking powder, baking soda and salt in a large mixing bowl.
Cut the butter into the flour mixture with a pastry blender until coarse crumbs form.
In another bowl whisk the buttermilk and vanilla together.
Add to the flour mixture with the blueberries just until the dough starts coming together.
Do not overmix.
Transfer the dough to a floured surface and knead gently a few times.
Form the dough into a 6 or 7-inch circle that’s approximately 1 to 2 inches thick.
Cut the circle in half, then cut each half into 4 pie-shaped wedges (or triangles).
Place scones on top of parchment paper-lined baking sheet.
Make an egg wash with egg and milk.
Brush the tops of the scones with egg wash.
Combine sugar and cinnamon and sprinkle over top of the scones, if desired.
Bake at 400º for approximately 20 minutes or until golden brown and a toothpick inserted in the center comes out clean.
Remove from oven.
Allow scones to cool about 5 minutes.
Drizzle glaze over top of scones.