In a bowl, add in the flour and 100 ml milk. Stir until there's no lump. Set aside.

In a pot, add in the water and 25 ml milk together with the cinnamon stick and lemon rinds. Bring it to a boil. While stirring, pour in the previously prepared flour milk mixture and cook until it thickens. Turn the heat off, set aside and let it cool for 5 minutes.

While stirring, pour in the beaten egg yolk. Mix to combine. Sift the mixture into a jar, it will be easier to pour the custard later. Leave it to cool completely before using.

Place the puff pastry sheet on a lightly floured working surface. Sprinkle the ground cinnamon on top and spread it evenly on the puff pastry. Roll the puff pastry gently and tightly into a log. Cut the log into 6 equal portions.

Take 1 portion and flatten it into a disk. Place in into a hole of a muffin pan (butter the muffin pan before hand). Gently press the dough against the hole until all the way up. The pastry will feel thin and don't worry because that's what we want. Make sure to press the dough all the way up the side. Repeat the same with the rest.

Pour the custard into the base just until ¾ way, do not pour more to avoid the custard spilling out when baking. Bake at 220°C (430°F) in preheated oven for 15-20 minutes or until the custard is slightly charred and the pastry is golden brown and fully cooked.

The egg tarts are best eaten when slightly warm. Enjoy!