Preheat your oven to 375°F (190°C). Roll out your pie crust and fit it into a 9-inch pie dish, trimming excess. Line with parchment paper and fill with weights. Bake for 15 minutes, then remove weights and bake for another 5 minutes until golden. Let cool.

In a saucepan, combine milk, cream, cinnamon, and vanilla over medium heat until steaming, but do not boil. If using, steep cinnamon stick or vanilla bean for 10 minutes before removing.

In a bowl, whisk eggs, sugar, and salt until pale and smooth for 2-3 minutes. Allow to come to room temperature.

Gradually pour the warm milk mixture into the egg mixture while whisking continuously. Strain through a sieve for a smooth filling if desired.

Lower oven to 325°F (160°C). Fill the crust with custard mixture just below the edge. Bake for 35-40 minutes until edges set and center jiggles slightly.

Cool at room temperature, then cover and refrigerate for at least 2 hours before serving.