For the wholemeal spelt sponge cake, separate the eggs. Whisk egg whites with cane sugar and vanilla sugar until foamy. Slowly add the yolks one by one. Stir in water briefly until a creamy light yellow mass is formed.
Slowly and carefully fold the spelt flour into the mixture. Spread on a baking tray lined with baking paper and bake in the preheated oven at 200 °C until hot, turn down to 170 °C and bake for about 5 minutes.
Check the pressure. After removing from the oven, either roll immediately into a roulade or leave to cool as a base for a sheet cake.