Step by step

Beat the eggs with the sugar in a bowl until the mixture whitens slightly. Incorporate the cornflour.

Tips
For pastry cream it’s important to use whole milk as the flavour will be stronger. If you want to give even more flavour to your cream you can add almond, lemon, or mandarin essence, depending on your preference.
Trivia
There are different types of pastry cream: lemon, chocolate or vanilla. To prepare the lemon pastry cream you can just add the lemon zest when starting to cook it; for the chocolate version you just add a tablespoon of cocoa when the pastry cream is cooked, mixing it in well to avoid lumps; whilst for the vanilla flavour you add a vanilla bean to the cream during cooking.