Beat the butter and sugar until frothy. Gradually add the eggs and whisk to a creamy mass. Stir in eggnog and rum. Sift flour and baking powder, add and mix in. Fold in cocoa powder, nuts and cinnamon. The dough is now more liquid than firm, but that`s right. Grease a suitable cake pan and sprinkle with breadcrumbs. Pour the dough into the mold.
Bake in the preheated oven at 175 ° C for about 50 minutes. Make a chopstick test.
Cover the cake with melted chocolate icing while it is still warm.