Smart (Magic) Custard Cake

The cake is "smart" because during baking it forms a sponge layer on top and a soft cream (similar to crème brûlée) underneath. Here is how to make it:

1. Separate the yolks from the whites. Beat the yolks together with the sugar, vanilla and water.
2. Then add the soft butter and beat for 1 more minute on high speed. Add the flour and beat again with the mixer.
3. Take a wire whisk and start adding the milk to the batter a little at a time. Whisk until all the milk is incorporated and you get a smooth, homogeneous mixture.
4. Beat the egg whites to stiff peaks and fold them into the milk mixture. Stir gently until the mixture absorbs the whites.
5. Pour the mixture into a greased and floured tin (about 25 cm in diameter). Bake at 170°C for about 45 minutes (but keep an eye on it, as every oven bakes differently). When it is done, open the oven door and switch it off. Leave the cake to cool down together with the oven.
6. When the cake is completely cold you can take it out of the tin. Dust it with icing sugar and serve. It is best chilled in the fridge.

An incredible dessert — a thin sponge layer forms on top and a cream underneath.