Lightly toast hazelnuts in pan, cool in a baking bowl.
Add all remaining ingredients and combine into a dough.
Cover and refrigerate for 2 hours.
Roll out dough to 7 mm thickness (between foil). Cut rectangles (2 x 4 cm), place on baking sheet lined with parchment paper, spacing them slightly apart.
Bake for about 4 minutes in the middle of the oven heated to 200 degrees.
After baking, brush with glaze while still hot.
Note: not a long shelf life (because of egg white and the short baking time).