• Preheat the oven to 400 degrees F. and set the oven rack to the middle position.
• Line a baking sheet with parchment paper and set aside.
• In a medium-sized bowl, gently toss flour, baking powder, baking soda, and salt. Set aside.
• In a separate small bowl, whisk sour cream and egg until completely smooth. Set aside.
• In a large bowl, stir sugar and orange zest together until sugar is moistened and zest is evenly distributed.
• Pour in flour mixture and toss to combine.
• Grate frozen butter into the mixture using a medium grater.
• Using your hands, work in the butter until the mixture resembles a coarse meal.
• Gently stir in sour cream mixture until just about combined. Do not overwork the dough.
• Very gently press the dough against the sides of the bowl a few times and form a ball. The dough will be sticky at first but will come together as you form it.
• Place dough on a lightly floured surface and gently pat into an 8" circle about 3/4" thick.
• Use a very sharp knife to cut into eight triangles (like a pizza).
• Transfer triangles onto the prepared baking sheet, leaving about 1" between.
• Bake scones for fifteen to seventeen minutes or until the tops begin to turn golden. Don't take them out too early or they will be too soft.
• . Allow them to cool for ten minutes on the baking sheet before transferring to a wire rack to finish cooling completely.

For the Glaze

• While the scones bake, prepare the glaze.
• Melt butter in a glass dish in the microwave for thirty seconds.
• Whisk in powdered sugar, vanilla, and orange juice until smooth.
• Once the scones are completely cooled, drizzle the glaze on the scone tops and sides with a spoon or a pastry brush.