For the lemon ring cake, separate the eggs and beat the egg whites until stiff. Beat the yolks, butter, sugar and vanilla sugar until very foamy.
Squeeze the lemon and grate the zest – mix the lemon juice and grated zest together with the milk with the yolk mixture. Mix flour with baking powder and fold into the mixture alternately with snow.
Pour the mixture into a greased cake pan and bake in a preheated oven at 160 °C for about 60 minutes.