Custard Tarts

My fiance absolutely loves custard tarts so I had a go a making some. With a bit of help from the BBC food website here is my attempt:

Ingredients:
(makes 12)

For the pastry:
200g ready-made puff pastry
30g  unsalted butter plus a little extra for greasing

For the filling:
125g caster sugar
30g cornflour
3 egg yokes
300ml single cream
50ml double cream
1 vanilla pod
1tsp vanilla essence

Method:
Roll out the puff pastry in a square until it is about 5mm thick
Spread the butter evenly over the pastry then cut in half
Place one half of pastry on top of the other then roll into a sausage
Cover the pastry and butter sausage and place in the fridge to cool

While the pastry is cooling make the filling:
Pre-heat the oven to 180C
In a pan, heat the egg yolks, sugar and cornflour over a low to medium heat, whisking continuously until thickened and well combined
Add the vanilla seeds and vanilla essence
Then add the milk and cream in a thin stream, whisking continuously, until the mixture is thick, smooth
Take the pan off the heat and continue to stir occasionally while it cools.

Grease a cupcake tin with butter
Take the pastry sausage out the fridge and cut into twelve equal slices
On a lightly floured surface roll each disk out until it has about a 7cm diameter
Press each pastry disk into the greased cupcake tin then fill with filling
Bake in the oven for about 20 mins until golden brown.