Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

In a large mixing bowl, whisk together the flour, sugar, baking powder, salt, and orange zest.

Cut cold unsalted butter into small cubes and mix into the dry ingredients until it resembles coarse crumbs.

In a separate bowl, whisk together egg, sour cream, heavy cream, and vanilla extract until smooth.

Pour the wet mixture into the dry ingredients and stir with a spatula until just combined.

Turn the dough out onto a floured surface, pat it into a circle, and cut into 8 equal triangles.

Place the triangles on the prepared baking sheet and brush the tops with heavy cream.

Bake in the preheated oven for 15-16 minutes or until golden brown.

Prepare the glaze by mixing powdered sugar with orange juice and extra zest if desired.

Drizzle the sweet orange glaze over the cooled scones generously.