Mix the eggs, softened butter, sugar and vanilla sugar well with the hand mixer. Then add flour, baking powder and milk and stir until frothy.
3. Now fill half of the mixture into the already greased Gugelhupf tin. Add the Nutella and cocoa powder to the rest of the dough and stir well. It may be that the dark dough is a bit more runny because of the Nutella, but that doesn`t matter!
Pour the dark mixture onto the dough in the Gugelhupf pan and use a fork to pull it spirally through the mixture to create a beautiful pattern.
Now bake the cake at 175 ° C (top / bottom heat) for 1 hour. After 55 minutes, do the chopsticks test to assess how long the cake still has to bake.