Oven 200 degrees. Use a 12 whole tart tin
Make the custard and chill it. Its great left over night as it thickens up beautifully and is quick and easy to spoon into the cases to pop into the oven just before you want to cook them
Put the cornflour,sugar,vanilla and yolks into a bowl with enough milk to blend thoroughly, with a whisk. Add the remaining liquid the milk and cream and pour into a small pot and cook over medium heat stirring constantly till it thickens. It will not split because it has cornflour in it, so don't e afraid to let it come to the boil. Pour into a bowl , cover with cling wrap and chill.
Spray your muffin tin. Fold 1 sheet of the puff pastry in half. Then roll into a sausage from the shortest side, so you have a thick short sausage ( this will make the layers). Pop back into the fridge for a minute, to firm up. Slice the sausage into equal sized discs. You should get about 6 or more from a sausage.* ( test the size of the first one, by rolling out very thinly and putting into the muffin tin, before cutting them all )
Put a little flour onto the bench and roll out the disc until it is rounded and thin and fits into your muffin tin. ( It doesn't need to be reach to the top of the muffin tine, just half way up the side) Fill the whole tin, then spoon in the custard leaving just a little room at the top.
Pop the tray into the oven for about 20-25 minutes. Take a peek and check that they are getting nice golden colour spots. ( you can turn the oven up for the last 5 minutes if they dont look like thaey are burnished enough.) They may still be a little soft and runny before they cool down
The pastry layers are mad and crazy and appear to be layered like a real Portuguese tarts ....don't skip this step.