Chocolate melt in a water bath. Beat egg whites with half the sugar until stable peaks.

Separately mix the egg yolks with the remaining sugar and cream cheese. Add sour cream, chocolate, vanilla sugar, starch and lemon zest. Mix everything until a homogeneous mass.

Gently into the cheese mass to introduce proteins. Put the dough in the baking dish.

The form with the dough put in a deep pan or other form of greater size. In the pan to half height to pour the boiling water and put in a preheated 180°C oven for 45-50 minutes. If you have a shape like I have split, they should be wrapped in cling film (this is to ensure that the water does not hit the batter and will not escape from the mold).

After baking cool the cake in the oven, then leave overnight in the fridge. Before serving, garnish with blackberries (also delicious and the strawberries and raspberries and other fresh berries).