Preheat oven to 400 degrees. Line a baking sheet with parchment paper.
In a large bowl, combine the flour, sugar, baking powder, baking soda, salt and orange zest. Add the butter and stir to combine.
In a separate bowl, combine the buttermilk, orange juice and egg; mix well.
Add the wet mixture to the dry mixture and stir until just combined. Gently fold in the raisins.
Turn out dough onto a lightly floured work surface and pat into an 8" circle. Cut dough into 8 wedges and transfer to the prepared baking sheet.
Brush tops of scones with the egg wash and sprinkle with sugar.
Bake for 18-20 minutes until golden brown. Transfer scones to a wire rack to cool.
Make the glaze:
In a small bowl, whisk together the powdered sugar and orange juice and zest until smooth. Drizzle the glaze over the cooled scones.
Notes
I rarely buy buttermilk because it's so easy to make with ingredients you likely have on hand. Just pour 1 tablespoon lemon juice or white vinegar in a measuring cup and add enough milk to hit the 1-cup line. Let the mixture sit at room temperature for 5-10 minutes until curdled.
Recipe by Two of a Kind at http://www.twoofakindcooks.com/orange-raisin-scones/