Put the egg yolks, sugar and cornstarch in a pan and whisk together. Gradually whisk in the milk until smooth.

Place the pan over a medium heat and cook, stirring, until the mixture thickens and comes to the boil. Remove from the heat and stir in the vanilla extract. Transfer the custard to a bowl, cover the surface with cling film to prevent a skin forming and leave to cool.

Lightly grease a 12 tray muffin pan.

Preheat the oven to 400 F degrees 200 C.

Use pre-rolled pastry, or roll out puff pastry to thin rectangle. Roll up the pastry tightly from the short end and cut the pastry log into 12 rounds, about 1/2 inch thick. Lay each pastry round on a lightly floured surface and use a rolling pin to roll out or press with the palm of your hand to create a really thin circle which will fit into the muffin tray.

Press the pastry rounds into the muffin tin.

Spoon the cooled custard into the pastry cases and bake for 20-25 minutes, or until the pastry and custard are golden. I will sometimes turn on the broiler for a few minutes to get a few extra burn marks which is a distinct feature of this tart.

Leave the tarts in the tin for 5 minutes, then transfer to a wire rack to cool completely.