For 30-40 pieces, crumble 500 g of sponge cake remains in a bowl. Melt 100 g dark chocolate and 25 g coconut fat (e.g. palmine) in a hot water bath. Add 6 tbsp. rum (alternatively orange juice or coffee) to the cake crumbs. Knead everything into a malleable mass, form into balls, roll in approx. 200 g chocolate crumbles. Chill for at least 1 hour.