Method

Lightly grease a 12 hole muffin tin and pre-heat oven to 200C/180C fan/Gas 6
Put the egg, yolks, sugar and cornflour in a pan and mix well together then gradually add the milk until mixture is well mixed and smooth, then add vanilla extract.
Place the pan on a medium heat and stir constantly until the mixture thickens and comes to the boil. Remove the pan from the heat and stir in the vanilla extract.
Put the custard mixture in a glass or ceramic bowl to cool and cover with cling film to prevent skin forming.
Cut pastry sheets into two pieces and place them on top of each other. Roll the pastry tightly, from the short side, into a log and cut the log into 12 even sized rounds.
On a lightly floured board, roll each round into a disc (approx. 10cm) and press the pastry discs into the muffin tin.
Spoon in the cooled custard mixture and bake for 20 to 25 minutes  until golden on top. Leave to cool in the tin for 5 minutes then move to a cooling rack to finish cooling – or they can be eaten warm.