Pour the egg yolks, sugar
into a saucepan
them together. Gradually beat in the cream and milk until smooth. Place the pan over medium heat, and stirring constantly, cook until the mixture thickens and comes to a boil. Switch off the heat, and stir in the vanilla extract. Transfer the custard to a bowl, cover the surface with plastic wrap
to prevent a skin from forming, and leave out to cool.
Preheat the oven to 375 degrees F. Lightly grease
a 12-count muffin pan.
Halve the puff pastry
sheet horizontally. Set one half on top of the other, and set it aside for 5 minutes. Tightly roll up the puff pastry from short end to short end. Cut the puff pastry log into 12 (1/2-inch) rounds. Lay each piece on a lightly floured surface, and using a rolling pin
, flatten out each round until they are 4-inches in diameter. Press each round into each muffin pan
. Spoon the cooled custard
into the pastry cases, and bake until the pastry and custards are golden, about 20 to 25 minutes. Leave the tarts in the pan for 5 minutes, and then remove and transfer to a wire rack to cool completely.