Add about ¾ of the milk into a pan, together with a slit open Vanilla bean. Scrape out the Vanilla seeds with a spoon or knife and add it to the milk and vanilla bean in the pot. Heatup the milk.
In a bowl mix the remaining milk smooth with the Cornflour, Sugar and Egg yolks.
Pick out and discard vanilla bean from the milk.
Keep on whisking your hot milk and pour in the Egg yolk milk mixture. Don't stop whisking or it will all burn on and the egg will be visible in little pieces. Just keep on whisking on low heat until the Cream starts to thicken, then keep it away from the heat.
Serve it hot with the Buchteln or you can use it with other desserts as well.