Preheat the oven to 200C/425F/Gas 7.
Place the flour, salt, butter and sugar into a food processor and pulse until the mixture resembles fine breadcrumbs.
Add the chocolate and milk and blend until the mixture is well combined and comes together as a dough. Turn the dough out onto a floured surface, knead lightly then pat down to 2.5cm/1in thick. Cut out six rounds using a pastry cutter, then place onto a non-stick baking sheet. Brush the tops of the scones with beaten egg.
Transfer to the oven and bake for 15 minutes, or until the scones are well risen and golden-brown. Leave to cool.
For the orange mascarpone cream, mix the mascarpone, icing sugar and orange juice and zest together in a bowl.
To serve, place the scones onto a serving plate with the bowl of orange mascarpone cream alongside.