Water 17~25ml
Whisk the egg yolk and mix with sugar using a whisk.
Mix cold milk + heavy cream + 1/2 vanilla bean over low heat to 60°C.
Divide the liquid into the yolks in two parts and mix with a whisk each time.
Cover closely with plastic wrap and refrigerate for 1 to 1.5 hours.
Make the tart dough, set it in a mold, and freeze.
Strain the filling, then pour 75g into each tart shell.
Preheat the oven to 190°C and bake at 180°C for 45~55 minutes.
Check constantly while baking.
If the tart shell is not enough, try making 1.8 times the original amount.