In a bowl, combine the sugar and hot water. Stir until the sugar dissolves completely, then let the mixture cool.

Once the sugar mixture has cooled, add the evaporated milk, eggs, vanilla extract, and salt. Whisk until fully combined.

Pour the custard mixture into the pre-made puff pastry shells, filling them evenly.

Preheat the oven to 375°F (190°C). Bake the filled pastry shells for approximately 20 minutes, or until the custard is set and the pastry is golden.

Allow the pastries to cool slightly before serving. Enjoy warm or at room temperature!