For the nut buns, whip the egg whites with the crystallized birch sugar until very stiff, pour just under 1/4 of the mixture into a freezer or snack bag.
Fold the nuts and the fine birch sugar into the rest of the mixture, fill into a piping bag and pipe small bushels onto a baking tray lined with baking paper.
Cut off a small corner of the snack bag and use the egg white mixture to pipe small dots onto the biscuits. Bake at approx. 150 °C for about 15 minutes.