Boil the pudding according to the instructions with only 400 ml milk and let it cool. Stir every now and then so that no skin forms.
Whip the cream, rub in the tonka bean and stir into the pudding.
Remove three tablespoons from the cherry juice. Bring the morello cherries to the boil in a saucepan, stir in the lemon juice, sugar and vanilla sugar.
Mix the cornstarch with the cherry juice until smooth and add this mixture to the boiling cherries. Bring to the boil and then cool.
In a dessert glass, first layer a spoonful of cherries, then pudding, again cherries and finally pudding again. Chill for another hour. Decorate with a cherry and the chocolate shavings.
In response to several inquiries, the explanation why there was no Mondamin. Mondamin is corn starch and makes grits or cake fillings cloudy. That doesn't happen with potato flour.