Grease and flour the bundt pan. Preheat the oven: top / bottom heat approx. 180 ° C, circulating air approx. 160 ° C.
Beat the margarine or butter until foamy. Gradually add sugar, vanilla sugar and salt while stirring, until a thickened mass is formed. Stir in each egg for about 1/2 minute at the highest level. Mix the flour with baking powder and stir in alternately with the milk in 2 portions briefly on a medium setting.
Mix the ready-to-bake poppy seed filling, eggs and egg liqueur together. Alternately fill the dough and poppy seed mixture into the Gugelhupf pan. With a fork, pull it clockwise through the dough and poppy seed mixture and bake the Gugelhupf for approx. 50 minutes. Take 10 minutes to remove the cake from the tin, turn it out onto a wire rack and let it cool. Melt the cake icing according to the instructions and cover the cake with it.