Mix the butter, sugar, vanilla sugar and a pinch of salt until frothy. Add the 5 eggs one after the other and stir in well. Mix the instant flour (no other!) With the baking powder and stir into the batter until a homogeneous mass is formed. Now add the egg liqueur while stirring constantly. Grease a springform pan with a rhodon insert, fill in half of the dough and smooth it out.
Stir approx. 2 - 3 tablespoons of Nutella into the remaining amount of dough until the dough has a brown color. Let the dark dough slide evenly onto the light dough and smooth it out.
Now use a small spoon to fold the dark dough all around under the light dough. This creates a nice pattern in the bleed.
Bake in the preheated oven at 180 ° C (gas: level 2-3) on the middle rack for about 1 hour.
Take the cake out of the oven and let it cool down a bit. Then remove from the mold and place on a cake rack to cool completely. Sprinkle with powdered sugar before serving.
Note: This cake is particularly moist for a dry cake. The egg liqueur and the Nutella bring together two fine flavors.
The cake can be kept for a good 1 week without losing its taste or freshness. It can also be frozen just as easily.