Beat the eggs, sugar, a little salt in a bowl until you get a fine mixture. Grate the zest and add the corn flour, yogurt and butter. Mix and add the white flour together with the starch and vanilla sugar. Mix both mixtures. Grease and the flour a kuglof meld, and pour the mixture. Bake 45 minutes at 180ºC.
Leave the kugloff to cool, and if you wish add season fruits, sprinkle with powder sugar and serve.