Separate the eggs and beat the egg whites until stiff.
Cream butter, egg yolks and the sugar. Add vanilla syrup and salt.
Add 1/2 tsp baking powder, water and milk. Stir in the flour and fold in the stiff egg whites.
Preheat the oven to 180 °C top/bottom heat.
Pour the batter into a greased pan and bake for 30-40 minutes.
Let the cake cool and serve as desired.