Preheat oven to 175°C.
Grease and sprinkle a spring form pan (24 cm diameter). Separate the eggs. Beat the egg yolks with the milk that has been pre-sweetened with Hermesetas Granulated sweetener. Mix the white flour, potato starch and baking powder. Whip egg whites with an egg whisk. Alternately add the flour mixture and egg yolks to the bowl with the egg whites. Mix well. Place the dough into the spring form pan. Bake for 40 minutes on a lower shelf in the oven. Allow the cake to cool and then turn.
Mix the milk, egg yolks, Hermesetas Granulated sweetener and cornflour in a pan. Bring to the boil and stir until the mixture is thickened. Cool in a water bath. Add vanilla sugar and curd. Cut the cake with a cake knife into two flat slices. Place one of these slices on a flat plate. Spread the pureed berries and the vanilla cream on the pastry base. Place the other slice on top.
Whip the cream and spread on the cake. Decorate with fruits and berries. Allow the tart to cool before serving.