Preheat the oven to 220C/200C Fan/Gas 7. Line a large baking tray.
Melt the chocolate in the microwave, in 20 second intervals, stirring in between to prevent burning. Let this cool.
Get the pastry out and roll to a large rectangle on the lined tray - essentially roll to the size of your baking tray.
Spread the melted (but not hot) orange chocolate down the middle of the rectangle, lengthways, creating a long rectangle of chocolate - leaving pastry on either side.
Use a sharp knife to cut slits about 3cm apart into the pastry on each side, up to where the chocolate is. Take these 'strips' of pastry and fold into the centre. A braid like shape will take form. Brush over the milk and sprinkle over a little sugar (optional).
Bake 20-25 mins until golden brown. Remove and let cool (at least a little) before serving!