Heat oven to 210C.
Blitz the butter, flour, baking powder, cayenne pepper, sugar and salt in a food processor for 10-15 seconds until coarse crumbs.
Pour the buttermilk into a mixing bowl, add the flour mixture and gently mix with a metal knife or spoon until the mixture is mostly coming together, but there are still floury and dough sections — be careful not to overwork it.
Mix the cheeses together and add to the dough.
On a lightly floured work surface, roll out the dough to 2½ cm thick. Starting from the outside of the dough, cut out the scones. Press straight down, don't twist the cutter. Lay a few centimetres apart on a parchment-lined baking tray.
Glaze with the extra buttermilk.
Bake for 12-15 minutes or until golden on top.
Take from the oven, leave to cool for 90 seconds or so, then transfer to a cake rack. This prevents them from getting a soggy bottom.
