Preheat the oven to 220C/425F/Gas 7.
Unroll the pastry and brush with water. Mix the sugar and cinnamon together in a bowl, then sprinkle over the pastry to lightly cover. Fold in both of the long ends of the pastry so that they meet in the middle. Brush with more water and sprinkle with more of the sugar mixture. Fold the pastry over again and slice 1cm/½in slices and place on a baking tray.
Place in the oven and bake for ten minutes, or until cooked through. Serve with whipped cream and oranges.