Combine milk, cream, sugar, vanilla sugar and cornflour in a saucepan and whisk until well combined. Slowly bring to the boil over medium heat and cook, stirring constantly, until thickened and mixture coats the back of a spoon, 10 to 15 minutes. Remove from heat.
Pour the mixture into 4 dessert bowls and allow to cool to room temperature, about 30 minutes. Refrigerate until chilled, 1 more hour. Sprinkle cinnamon on top before serving, if you like.