Heat the blackberries with sugar and apple juice and simmer for 5 minutes, then let cool.
Mix 50 ml of milk with the yolks and the vanilla pudding powder.
Heat the remaining milk with sugar and vanilla sugar until it boils, remove from heat, stir in the yolks-vanilla custard mixture and whisk well.
Pour the vanilla custard into dessert bowls, top with the blackberries including their juice and serve.