Preheat oven to 220°C.
Roll out puff pastry and place into tart molds.
In a pan, heat milk and sugar until dissolved.
Mix egg yolks and cornstarch in a bowl.
Slowly add warm milk mixture while stirring.
Cook gently until slightly thickened.
Add vanilla extract and mix.
Pour custard into pastry shells.
Bake for 15–20 minutes until tops are slightly browned.
Let cool slightly and serve.