Wash the oranges, grate them dry and thinly grate the peel of 1 orange. Halve the orange and squeeze it. Cut butter into pieces. Cream butter, orange peel, sugar, vanillin sugar and 1 pinch of salt with the whisk of the hand mixer. Stir in the eggs one by one. Mix flour and baking powder and stir in alternately with 5 tablespoons of orange juice.
Put half of the dough into a greased, flour-spread ring cake mould (2.5 litres capacity). Stir poppy seed baking into the other half of the dough and put it into the ring cake tin. Marble the dough with a fork. Bake in the preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for 50-55 minutes. Take the cake out of the oven and after about 15 minutes turn out onto a cake rack. Let the cake cool down. Sift icing sugar into a bowl. Mix icing sugar, egg white and lemon juice to a thick icing. Partially cover the cake with the icing. Sprinkle some poppy seeds on the moist icing and let it dry for about 1 hour. Cut the orange in half and 1/2 orange first into slices, then into corners.
Let the cake cool down. Sift icing sugar into a bowl. Mix icing sugar, egg white and lemon juice to a thick icing. Partially cover the cake with the icing. Sprinkle some poppy seeds on the moist icing and let it dry for about 1 hour. Cut the orange in half and 1/2 orange first into slices, then into corners. Before serving, decorate the cake with the orange corners. Whipped cream tastes good with it
2 hours waiting time