Prepare a large baking sheet with parchment paper and set aside.
Whisk together the flour, sugar, baking powder and salt in a large bowl.
With a pastry cutter or fork, cut in the butter until almost fully incorporated, then fold in the blackberries gently.
In a separate bowl, whisk together the milk, egg, and maple syrup.
Pour the wet ingredients over the dry, mixing until just barely combined. Mixture should be rough at this stage.
Move the dough to a floured surface and gently knead the dough into a rough ball.
Form dough into a flattened circle and cut 6-8 wedges, placing them slightly apart on your prepared baking sheet.
Chill scones in the fridge while you preheat your oven to 400ºF.
For the egg wash: whisk egg and water together, then brush the wash over the tops of each scone. Sprinkle with coarse sugar before baking as well. If you want a lighter finish on your scones, simply brush with milk and top with sugar.
Bake for 20 minutes or until golden brown and risen.
While scones cool slightly, whisk together the milk, maple syrup and powdered sugar for the glaze. Drizzle over the top of your scones before serving.