Preheat your oven to 500°F (250°C) to ensure a nice crisp finish.

In a saucepan, combine the sugar, water, and cinnamon stick. Bring to a boil, stirring until sugar dissolves. Reduce heat and let it simmer for 10 minutes. Remove from heat and allow it to cool.

In another bowl, whisk together the whole milk, double cream, egg yolks, egg, vanilla extract, and cornstarch until smooth.

Gradually add the cooled sugar syrup from the first step, combining everything well.

Roll out the puff pastry and cut it into circles that fit your tart molds.

Place the pastry circles into the molds and fill them with the custard mixture, making sure not to overfill.

Bake for about 15-20 minutes or until the tops are golden brown and caramelized.