Mama Chan has made these for years and years. They are up there with the classic custard tarts you get from a Chinese bakery.

Custard:
500 ml milk
¾ c sugar
3 eggs
1 tsp white vinegar

Flakey pastry:
1 c flour
125 g butter
½ small c milk
1 tsp vinegar

This recipe makes 18 tarts.
Heat milk to almost boiling. Stir in sugar to dissolve. When cool add eggs and vinegar and beat lightly until mixed.

Grate cold butter into flour. Add vinegar and milk. Bring together to form a dough. Roll out to a rectangle and fold 3 or 4 times to make smaller rectangle. Leave in fridge for 30 mins (or you can leave it overnight in a plastic bag if you’re baking the next day).
Roll out and cut into circles about 11.5 cm circumference to fit your muffin tin. Put back into fridge to firm.
When custard has cooled down fill the muffin tins ¾ full.
Bake at 180 C for 30-35 mins or until pastry is cooked.