Move the baking rack to upper third of the oven. Preheat oven to 400°F. Prepare baking sheets with parchment paper or silicone baking mat.
In a large bowl, combine flour, baking soda, baking powder, salt, and sugar. Whisk together.
Cut cold butter into ½ inch cubes. Using a pastry cutter, cut the butter into the flour mixture until there are no remaining large chunks of butter and the mixture resembles coarse meal. Place in freezer for 10 minutes to chill.
While this chills, in a large measuring cup, whisk together the buttermilk and egg. Zest the orange and toss orange zest and raisins in a teaspoon of flour until lightly coated. Set both aside.
Prepare the egg wash, beating together an egg and the buttermilk in a small bowl. Set aside.
Remove flour mixture from the freezer. Add raisins and orange zest in and mix.
Create a small well in the flour mixture and slowly pour the buttermilk and egg into the well. Using a dough whisk or wooden spoon, mix the dough together until just combined.
On a floured surface, knead the dough about 5 times folding it over itself, until it comes together. Do not over-knead.
Flatten out the dough to about ¾ inch thickness. Using a biscuit cutter, cut out scones by pushing firmly down without a twisting action.
Space scones evenly on prepared baking sheet and generously brush with egg wash. Sprinkle tops with sugar.
Once scones are placed in the oven, immediately increase the temperature to 425°F. Bake for 10-12 minutes until the tops are a golden brown. Remove from oven and transfer to a cooling rack to cool briefly. Serve warm with butter and jam or clotted cream.
