01 - Set oven temperature to 400 degrees Fahrenheit and line a baking sheet with parchment paper.
02 - Whisk together flour, sugar, baking powder, and salt in a large mixing bowl until evenly combined.
03 - Add cold, cubed butter to dry ingredients and cut in using a pastry cutter or fingertips until mixture resembles coarse crumbs.
04 - In a separate bowl, whisk heavy cream, egg, orange zest, and vanilla extract until fully blended.
05 - Pour wet ingredients into dry and stir gently until just combined, avoiding overmixing.
06 - Gently fold chopped dark chocolate into the dough until evenly distributed.
07 - Turn dough onto lightly floured surface, shape into a 1-inch thick disk, then cut into 8 wedges.
08 - Arrange wedges on baking sheet spaced apart, brush tops with additional cream, and sprinkle with turbinado sugar if desired.
09 - Bake for 16 to 18 minutes until tops are golden and scones are cooked through.
10 - Transfer scones to a wire rack and allow to cool slightly before serving.