Preheat the oven to 200C/400F/Gas Mark 6.
Sprinkle a cutting board or other work surface with the brown sugar. Place the puff pastry on top of the brown sugar and roll it out into an approximately 12 x 18cm rectangle. Sprinkle with more brown sugar over and fold into 3.
Roll once more with brown sugar on the work surface until measuring 12x18 cm. then spread the dough evenly with the raspberry jam.
Starting from the long edge, gently roll or fold the dough toward the centre. Repeat from the opposite side until both sides are rolled together and meet in the centre of the dough. Wrap the dough in cling film and place in the freezer for about 10 minutes until firm but not frozen.
Remove the rolls from the freezer and using a sharp knife slice into 1” thick pieces. Lay each slice onto the baking tray, and brush well with the egg wash.
Place in the preheated oven for 15 – 20 minutes, until puffed up and golden.
When baked, remove from the oven and allow to cool.
Dust with icing sugar and serve.