Beat egg whites with salt until stiff.
Beat butter, sugar, vanilla sugar, yolks, lemon juice and lemon zest until creamy. Stir in the curd cheese.
Mix semolina, pudding powder and baking powder and stir into the curd mixture, fold beaten egg whites into the curd mixture and pour into a greased loaf pan.
Bake in the preheated oven at 180 °C top/bottom heat for about 55 minutes. Allow to cool in the turned-off, slightly open oven (this ensures that the cake retains its shape).
Turn out of the pan while still warm and sprinkle with powdered sugar as desired.