Preheat the oven to 375°F/190°C. Line a baking sheet with parchment paper or a silicone baking mat. Set aside.

In a large bowl, sift together flour, baking powder, and cocoa powder. Stir in sugar. Cut in the butter using a pastry blender or use your fingertips to rub in the butter, until the mixture resembles fine crumbs, and there are small uneven pieces of butter throughout.

Add white and milk chocolate and mix to distribute them evenly.

Make a well in the center of the mixture, add the egg and vanilla, then add the milk gradually, mixing with a rubber spatula. Stop adding milk once you get a firm dough. Don’t overmix.

Transfer dough to a floured surface and pat dough into a circle, about 1-inch (3 cm) thick. Using a 2.5-inch (6.5 cm) biscuit cutter, cut out about 6 rounds. Press the leftover dough into another ¾-inch thick piece and repeat the process to get 2-3 more biscuits.

Place scones on prepared baking sheet, 2-inches apart. Bake for 15-20 minutes until cooked through, and springy to the touch. Transfer scones to a wire rack and leave to cool. Drizzle melted chocolate over the scones, if you like.

Scones are best eaten the same day they are made, but leftovers can be frozen for 2 months. Reheat in the oven before serving.