Preheat the oven to 175 ° C. Beat the butter, sugar and eggs until frothy. Add rum, milk and cocoa powder and stir thoroughly for a long time. Mix the flour, hazelnuts and baking powder, add to the dough and stir again very thoroughly. It is important to stir the cake batter very well and for a long time so that the cake is nice and creamy.
Now grease a cup cake pan and sprinkle with breadcrumbs. Pour in the cake batter and smooth it out. Bake in the oven at 175 ° C for about 60 minutes (stick test). Dust the finished and cooled cake with powdered sugar.