1 vanilla bean, split and seeds scraped
6 egg yolks
100g caster sugar
25g plain flour
1 tsp caster sugar, for dusting
Sprinkle 2 tbs of sugar over the base of a large, heavy bottomed saucepan - this will melt and coat the bottom of the pan to help prevent the milk burning.
Add milk, vanilla bean and seeds - bring to the boil and simmer for 5 minutes. Remove from the heat and remove vanilla bean.
Mix together the egg yolks and sugar until creamy. Add flour and cornflour and whisk until combined. It is important to whisk until all graininess is removed.
Pour ⅓ of the milk and vanilla mixture into the egg, sugar and flour mixture and whisk until well combined. Pour back into the remaining milk, return to the heat and simmer for 30 seconds, whisking continuously. Do not boil!
Transfer to a bowl or container, cover with plastic wrap directly touching the surface (to prevent a skin from forming) and cool down on ice as soon as possible to prevent the growth of harmful bacteria. Seal with plastic wrap and refrigerate until needed