For the vanilla pudding with chocolate sauce, mix sugar and cornflour. Stir in the yolks and 5 tablespoons of milk until smooth.
Bring the remaining milk to a boil with the pulp of the vanilla bean, reduce the heat and stir in the sugar-yolk mixture.
Stir constantly until the mixture begins to set. Pour into custard cups and refrigerate the custard.
For the chocolate sauce, heat the milk and stir in the chopped chocolate along with the Ovaltine until a smooth sauce is formed.
Turn the cooled pudding out onto a plate and serve the vanilla pudding with chocolate sauce.