Pre-heat oven to 220ºC (200ºC fan-forced), line two baking trays with baking paper.
Place flour and butter in a large bowl. Using fingertips, rub butter into flour mixture until mixture resembles fine breadcrumbs.
Lightly beat the eggs and add to the flour mixture. Add the sugar and buttermilk to the flour mixture and mix with a stand mixer on low speed or by hand until mixture forms a dough. Be careful to not over mix the dough.
Bring the dough together on a lightly floured bench and press out to 3cm thick. Dip a 6cm round cutter into flour to prevent dough sticking. Cut out scones. Gently press leftover dough pieces together and repeat to make a total 22 scones.
Beat together the remaining buttermilk, the egg yolk and pinch of salt and brush the tops of the scones.
Place the scones in the oven for 12-15 minutes, swapping the trays half way through and bake until golden.