Combine flour and salt. Cut butter cubes into flour. Add water and mix to form a loose dough. Dump out onto table and pat dough into a rectangle.
Roll out to 1/2 inch in thickness. Fold dough into thirds and turn it a quarter to the right.
Roll the folded dough into a rectangle 1/2 inch in thickness and fold into thirds again. Wrap the dough in plastic wrap and chill for 15-30 minutes.
Repeat rolling and folding four more times. Its best to chill after every two turns.
Beat together yolks, sugar, cream, milk, and vanilla paste with a whisk. Continue to whisk over a bain-marie until sugar has dissolved. Strain mixture.
Roll out puff pastry into a log. Portion out 30 g balls of dough. Use scaled dough to line muffin tin.
Divide custard mixture into prepared tart shells. Bake in a preheated 400 degree F oven for 15-20 minutes. Then 3-5 minutes in the broiler.