Preheat the oven to 250°C (482°F)

Roll the puff pastry evenly and thinly. Use a round cookies cutter, cut out 12 circular discs to fit in the aluminium foil shells. Gently use fingers to adjust the shape to of the pastries, ensure it fits well. Do not stretch the pastries.

Cover the puff pastries with parchment paper. Put pie weights on the pastries and bake for 10 minutes at the middle deck.

In a measuring cup, mix hot water (boiled) with salt and white sugar. Stir it until all the sugar and salt are dissolved.

Add evaporated milk in the mixture, mix and combine.

In a small bowl, crack two eggs and beat the eggs until they are mixed well.

Pour the egg mixture into the water-milk mixture gradually, stir at the same time to ensure they are well combined.

Prepare another measuring cup and put a sieve on top of it. Pour the mixture into the new measuring cup through the sieve to remove any unmixed eggs or egg shells.

Put the tarts into the preheated oven at the middle deck and bake for 20 mins.

After 20 mins, when the egg custards started to expand and rise, put the baking tray at the top deck to bake for another 10 mins to give the tarts a caramelized surface.