Melt butter in a saucepan. Add apples and cook for two minutes. Add water, cinnamon, allspice, nutmeg, and brown sugar and continue cooking for 6-8 minutes.
Put chocolate hazelnut spread over unrolled puff pastry.
Cut into 9 squares, and top each square with the apples you just cooked.
Fold over each square to create a triangle and close seams with a fork. Brush egg white on top, and sprinkle with a little cinnamon and sugar.