Special equipment: 5 1/2-centimeter (about 2-inch) cutter
Heat your oven to 220 degrees C (425 degrees F). Line 2 baking trays with parchment paper.
Place the flour, butter, sugar and baking powder into a mixing bowl. Rub the ingredients together to form a breadcrumb-like mixture. Add 2 eggs and turn the mixture gently to incorporate the ingredients. Add half the milk and keep turning the mixture to combine. Add the remaining milk a little at a time to form a soft dough.
Place the dough on a floured surface. Use your hands to fold the dough in half and then turn 90 degrees and repeat. Do this a few times until the dough is smooth. (If you are making flavored scones, add the walnuts or raisins now.) Continue dusting the work surface with flour if the dough is sticking. Do not overwork the dough.
Roll the dough to 2 1/2 centimeters (about 1 inch) thick. Using a 5 1/2-centimeter (about 2-inch) cutter dipped in flour, stamp out rounds and place them on the prepared trays. Try not to twist the cutter; just press down and then lift up and push out the dough. Re-roll any remaining dough and cut out more scones.
Let the scones rest for a few minutes. Brush the tops of the scones with the beaten egg, being careful not to let the egg run down the sides.
Bake until golden and well risen, about 15 minutes. Leave to cool and then split in half and enjoy with butter or clotted cream and jam.