Begin by whisking together the flour, sugar, salt, and baking powder in a large bowl. Using a pastry cutter or your hands, incorporate the cold butter into the dry ingredients until the mixture forms a crumbly texture.
In a separate small bowl, whisk the egg, buttermilk, and vanilla extract. Add this mixture, along with the cranberries and orange zest, to the dry ingredients. Stir gently until just combined and the dough holds together in a ball.
Lightly flour a sheet of parchment paper or your work surface. Shape the dough into an 8-inch circle, approximately ¾ inch thick. Brush the top with additional buttermilk to give the scones a golden finish.
Cut the dough into 8 wedges using a sharp knife. Arrange the scones on a baking sheet lined with parchment paper or a silicone mat, ensuring they are spaced out to allow for expansion during baking.
Refrigerate the scones for 20 minutes. While they chill, preheat your oven to 400°F (200°C).
Bake the scones for 20 to 25 minutes, or until they turn a golden brown. Remove from the oven and allow them to cool slightly.
While the scones cool, prepare the glaze by whisking together the powdered sugar, orange juice (or milk), and vanilla extract until smooth. Drizzle the glaze generously over the tops of the scones. If you prefer an even stronger orange flavor, feel free to add extra orange zest to the glaze.
Serve the scones warm or allow them to cool completely before storing in an airtight container.