Place the flour, sugar, baking powder and salt into the bowl of a stand mixer and mix together until combined.
Add the chilled butter and mix on low speed until the butter is rubbed in and the mixture resembles breadcrumbs.
In a small bowl, whisk together the buttermilk and eggs. Pour this mixture into the mixer and mix on low-speed until a uniform dough is formed.
Tip the scone dough out onto a lightly floured work surface and dust the top of the dough too.
To knead the dough, very lightly fold and press the dough, repeating until the dough is smooth and supple.
Form the dough into a ball and cover with clingfilm. Rest for 30-60 minutes.
Remove the clingfilm and turn the dough over so the smoothest side is face down. Roll out until the dough is 2cm thick.
Use a 5cm round cookie cutter to cut out the scones, dipping in flour between cuts to prevent sticking.
Place the scones, smooth side up onto a parchment-lined baking tray. Cover with clingfilm and rest for an hour before baking.
Preheat the oven to 190ºC (170ºC Fan). For the egg wash, beat together the egg yolk, splash of cream and a pinch of salt.
Brush the tops of the scones with the egg wash, being careful to prevent it from dripping down the sides.
Bake the scones for about 15 minutes or until the tops are golden. Remove and set aside to cool.
Serve warm with clotted cream and jam.
