Mix eggs, powdered sugar and vanilla sugar until frothy. Then stir in the oil and egg liqueur. Then add buckwheat flour, potato flour and baking powder. Stir in everything and pour the batter into a greased bundt cake pan.
Bake in a preheated oven at 150 ° C for about 60 minutes.
After baking, let the cake stand in the pan and only then turn it out.
Tip: If you have taken 350 ml egg liqueur, the baking time is 70 minutes.