Separate the egg whites in a bowl and beat them with the sugar until stiff. Grate the chocolate finely and stir it with the nuts, the rum, and the cinnamon in the eggs. Let the dough rest in the fridge for at least four hours or even better overnight.

Preheat the oven to 180 degrees. Take small portions off the dough with a teaspoon. Form small balls (about two centimeter diameter) out of the dough with wet hands. Put the balls on two baking sheets covered with baking paper and bake them in the preheated oven at 180 degrees for about 15 minutes. Let the biscuits cool down. Dip them half in the melted chocolate.