Dry-roast the hazelnuts and sugar in a frying pan for approx. 3 mins., allow to cool.
Unroll the pastry, cut in half lengthwise, then cut into 7 rectangular pieces (6 x 12 cm), place half on a baking tray lined with baking paper. Spread 1 tbsp the nut sugar on the pastry, leaving a border of approx. 5 mm., brush with a little egg. Set aside the remaining nut sugar. Top with chocolate and fruit. Make incisions in the remaining pastry pieces with a sharp knife, about 5 mm apart, so that the pieces still hold together around the edges. Place pastry pieces over the filling, press edges together firmly with a fork. Coat the slices with the remaining egg.
Approx. 10 mins. in the centre of an oven preheated to 220°C. Sprinkle the remaining nut sugar over the pastry slices, bake for approx. 10 mins. until done. Remove from the oven, leave to cool on a cooling rack.
Serve the slices with a scoop of ice cream.