In the bowl of a food processor, combine flour, sugar, orange zest, baking powder, salt and frozen (or very cold butter) cut up into 1 tablespoon sized pieces.
Pulse 3-5 times until the butter pieces are the size of small peas.
Note: If you do not have a food processor, you can grate the frozen butter with a cheese grater and cut it in to the bowl of dry ingredients with a pastry cutter.
Transfer the dry ingredients to a medium sized mixing bowl and set aside.
In a small mixing bowl, combine buttermilk (or heavy cream), egg and vanilla extract and lightly beat with a fork until just combined.
Pour the wet ingredients into the bowl with the dry ingredients and fold together until it just combines into a ball.
Next, transfer the ball to a parchment lined plate and pat down into a 6 inch disk.
Freeze for 1-3 hours if making day of or overnight if making in advance.
Preheat oven to 400 degrees Fahrenheit and line a large baking sheet with parchment paper.
Using a bench scraper. Cut the dough in the middle vertically, then horizontally creating 4 equal pieces. Then cut each piece in half again creating 8 triangular pieces like a pizza.
Brush the top of each scone piece with buttermilk or heavy cream.
Place each slice on the parchment lined baking sheet and bake for about 20-23 minutes until the tops start to become golden brown.
Transfer to a wire rack to cool while you make the glaze.
In a small bowl, combine powdered sugar and 1 tablespoon of fresh squeezed orange juice. Stir together with a whisk until you have a thick paste. Then add a few drops more at a time and continue stirring until you reach your desired consistency.
Using the whisk, drizzle the glaze above the scones back and forth until you reach the desired amount.