Beat the eggs, icing sugar and vanillin sugar with the whisk of the hand mixer until thick and creamy. Slowly add the oil and egg liqueur and mix together. Mix flour, potato flour and baking powder, sieve over it and mix in until a smooth dough is formed.
Grease a wreath mould (26 cm Ø), sprinkle with breadcrumbs and fill in the dough, smooth it down. Bake in the preheated oven (electric: 175 °C/ gas: level 2) for approx. 90 minutes. Results in approx. 24 pieces.