Melt the chocolate coating over a bain-marie and allow to cool slightly.
Cream butter and sugar until fluffy. Add softened chocolate, cocoa, coffee powder, rum and hazelnuts. Mix until a smooth, fluffy mass is formed.
Spread 1/3 of the hazelnut mixture on a wafer, cover with another and press down well. Spread the second third of the mixture on top and cover with a third wafer, pressing down again. Spread the last third of hazelnut mixture and cover with the last wafer. Press the layers down evenly again: This works with a large cutting board, for example. Chill in the refrigerator for at least 2 hours.
Cut the chilled wafer-hazelnut plate into small slices (or other shapes to taste) with a very sharp knife and refrigerate.
Preparation Tip:
For those who find the domestic production of wafers too time-consuming, simply roll the hazelnut mass into balls in the classic way!