Preheat your oven to 375°F (190°C). Fit the pie crust into a 9-inch pie dish and line with parchment paper and weights. Bake for 15 minutes, then remove the weights and parchment. Bake for an additional 5 minutes until lightly golden.

In a medium saucepan over medium heat, combine the whole milk, heavy cream, ground cinnamon, and vanilla extract. Heat until steaming but do not boil.

In a large mixing bowl, whisk together the eggs, granulated sugar, and salt until pale and smooth.

Gradually pour the hot cream mixture into the egg mixture while continuously whisking to prevent scrambling.

Lower the oven temperature to 325°F (160°C). Pour the custard into the pre-baked pie crust and bake for 35-40 minutes.

Let the pie cool to room temperature on a wire rack, then cover and refrigerate for at least 2 hours.