Cream butter well, then alternately stir in vanilla sugar, eggs, sugar, mixture of flour and baking powder, coffee and cocoa. Finally, gently fold in rum, grated chocolate and grated nuts.
Pour into a greased cake pan and bake in a heated oven at 175 °C on the middle shelf. Test the cake with a chopstick !
Turn the cake out onto a wire rack and cover with the icing. Mix powdered sugar with cinnamon, stir with rum and water.
Leave the cake to infuse for a few days so that the aroma can fully develop. The recipe can be modified for kids : instead of coffee beans a little more flour and baking powder, instead of rum for the dough milk.