In a large bowl, whisk together flour, sugar, salt and baking powder
Using a pastry blender or your hands, cut in butter until mixture is crumbly
In a small bowl, whisk together eggs, buttermilk or cream, and vanilla extract
Add liquid ingredients and blueberries to dry ingredients and stir until moistened, and mixture is well combined and holds together
Sprinkle a small amount of flour onto parchment paper or counter
Press dough into 8 inch circle, about ¾ inch thick
Brush top with additional buttermilk or cream
Sprinkle with cinnamon sugar mixture or coarse sugar, if desired
Using a sharp knife, cut circle into 8 wedges, pizza-style
Divide triangles and place on baking sheet lined with parchment paper or silicone mat, leaving enough space for the scones to expand when cooked
Place in refrigerator for 15-30 minutes
Preheat oven to 400 degrees F
Bake for 20-25 minutes or until golden brown
Remove from oven and cool slightly
Add powdered sugar glaze, if desired
Serve warm or at room temperature
Store leftovers in airtight container at room temperature