Preheat the oven to 200 degrees Celsius. Grease a baking tray and line it with parchment paper.
In a food processor, combine all-purpose flour, cold and cubed butter, baking powder, salt, red chilli flakes, and peri-peri seasoning. Blitz until the mixture resembles bread crumbs.
Add grated cheddar cheese to the mixture and gradually pour in the buttermilk. Set aside a small amount of buttermilk for brushing the scones.
Transfer the dough from the food processor to a bowl. Gently bring the dough together with a light hand.
On a floured surface, roll the dough to a thickness of 2 inches. Cut with a round cutter and place the scones on the prepared baking tray. Re-roll the remaining dough and cut again.
Rest the scone dough in the refrigerator for half an hour.
Brush the scones with the reserved buttermilk and bake in the preheated oven for 15 minutes or until they turn golden and crisp.
Cool the scones at room temperature or serve them warm.

To make buttermilk, combine 1 cup of milk with 1 tablespoon of white vinegar or lemon juice, stir, and let it sit for 5 minutes until it thickens. Alternatively, dilute 1/2 cup of plain yoghurt with 1/2 cup of water to achieve a similar consistency.