Pre-heat your oven to 220˚C or 200˚C fan
Grease a large baking tray with spray butter, or smear with butter, and set to one side.
First, sift the flour and baking powder into a bowl and then give it a gentle stir to make sure the baking powder is evenly distributed.
With cold hands, rub the butter into the flour, until it looks like breadcrumbs.
Then stir in the sugar.
Break the egg into a measuring jug and add enough buttermilk to make 150ml of liquid. Lightly beat with a fork to mix.
Add the liquid to your flour mixture and mix gently until it is only just combined and has formed a soft dough.
Turn your dough on to a (very) lightly dusted worktop and roll out until it is about 1 cm deep.
Use a 5cm pastry cutter to cut out your scones. Be sure twist your cutter as you push it down. Then place each one upside down on your buttered tray.
You can re-roll the dough once to get more scones, but any more than that and they will start to become quite tough.
Brush them with milk or beaten egg and bake for 10-12 minutes, or until they are lovely and golden.
Dust with icing sugar and serve while still warm.