Portuguese egg tart

To me, this is the cheat's version of the HK or Cantonese egg tart because it's 'hardier' and the egg custard isn't soft and quivering like the Cantonese one. This also uses puff pastry, which in my case, has already been ready made. Therefore, this recipe is like the introduction to baking egg custard and if I get this right, I can move on to the pale HK egg tarts.

Recipe adapted from https://www.littlesweetbaker.com/2016/01/29/chinese-egg-tarts/
She used 2 eggs and 1 yolk but as I can never figure out what to do with the extra white so I added it in. Maybe that puffed it up more than normal.

Ingredients (makes 16 to 20 tarts)
2 sheets puff pastry, thawed
3 eggs, beaten
⅓ C + 1 tbsp (80g) sugar
⅔ C warm milk
⅓ C evaporated milk
½ tsp vanilla essence

Method
1) Warm up the milk and melt the sugar. Let it come to room temp. Preheat oven to 200 deg C and place the oven shelf at the lowest third of the oven.
2) Beat the eggs with evaporated milk and vanilla. Add the sugary milk. Strain into a pouring jug.
3) Unfold the pastry sheet and lay it over a lightly floured surface.
4) Using a round cookie cutter (9cm for tart tin and 10cm for muffin tin), cut out as many rounds as you can squeeze in. Place them into the oiled tart or muffin tins. Trim off any excess.
5) Pour the egg mixture into the pastry case but leave a rim. Do not fill to the brim or over fill or else the mixture will overflow during baking and stick the tart to the tin.
6) Bake the tarts at 200 deg C for 15 minutes. In the last 5 minutes, watch out for when they start to puff up. Open the oven to let out the hot air escape. If not, they will deflate after removal from the oven. Reduce the temp to 175 deg C and then bake for a further 14 minutes (tart tin) to 16 minutes (muffin tin). Check for readiness by inserting a toothpick which will stand upright unaided.
7) Remove from oven and leave to cool in the tins. Once the tins are cool enough to handle, remove from the tin. Once fully cooled, store in an airtight container.