Steps
1. In a saucepan, heat the milk and vanilla bean (seeds and pod) over medium heat until steaming. Remove from heat and let it infuse for 15 minutes.
2. In a bowl, whisk together egg yolks, sugar, and cornstarch until pale.
3. Slowly pour the warm milk into the egg mixture, whisking constantly.
4. Return the mixture to the saucepan and cook over low heat, stirring constantly, until thickened.
5. Remove from heat, discard the vanilla bean pod, and stir in vanilla extract.
6. Transfer the creme patisserie to a bowl, cover with plastic wrap (directly touching the surface), and chill before using.