Whisk 5 sachets vanilla pudding powder with a little of the 1.5 l milk until smooth.

Bring the remaining milk to a boil, then whisk in the pudding mixture.

Cook the vanilla pudding until thickened, then cover its surface with plastic wrap.

Cool the pudding until warm or room temperature, then melt the 100 g white chocolate.

Beat 250 g butter with 180 g powdered sugar until pale and fluffy.

Beat the cooled pudding and melted white chocolate into the butter mixture until smooth.

Cook 400 g mixed berries with 4 tbsp granulated sugar until the fruit becomes soft and jam-like.

Blend the cooked fruit until smooth, or leave some fruit pieces for texture.

Whisk 1 vanilla pudding sachet and 1 tbsp cornstarch into 300 ml water until lump-free.

Stir the water mixture into the hot fruit, then cook for a few minutes until thickened.

Place one rozen cake layer on the cake board, then spread it with vanilla cream.

Add a second cake layer and vanilla cream, then add a third cake layer and hot fruit filling.

Continue layering cake sheets with vanilla cream and fruit filling, using fruit filling three times in total.

Cover the assembled cake with the remaining vanilla cream, then chill overnight.

Whip 200 ml whipping cream until firm, then decorate the chilled cake before serving.