Measure the self raising flour and baking powder into a mixing bowl. Stir briefly to combine, add the cubed butter and rub it in with your fingertips until the mixture resembles fine breadcrumbs.
Stir in the sugar. Combine the buttermilk and egg in a measuring jug and gradually add to the mixing bowl, stirring it in until you have a soft sticky dough.
Tip the dough onto your worktop and pat it into a square shape about 1-2 cm high (slightly less tall than your 6cm fluted cutter). Cut out the scones by pressing the cutter straight down into the dough and lifting it out without twisting.
Repeat until you have used up all of the dough, gathering any scraps. Brush the top of the scones (not the sides) with a little milk and sprinkle with Demerara sugar.
Preheat the Air Fryer for five minutes to 180°C (350°F) then place the scones on a liner in the basket, spaced apart to allow the air to circulate. Bake for 15 minutes or until the scones are well risen and golden.
Take the scones out of the air fryer and cover with a clean tea towel. Allow them to cool down slightly before serving with clotted cream and jam.
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Notes
Use butter that's firm but not super cold. Avoid using soft butter as it can make the scones greasy.
Avoid twisting the cutter as you press into the dough and as you lift it out. This helps the scones to rise evenly.
Make sure the flour and baking powder are fresh!
Store the scones in an air tight container for 3-4 days and freshen them up by heating in the air fryer for a couple of minutes before serving.
Freeze the scones for up to three months.
If you would like to bake the scones in the oven then preheat it to 200°C (400°F) and bake the scones for 15 minutes.