Preheat your oven to 375°F (190°C). Roll out your pie crust and fit it into a 9-inch pie dish. Line the crust with parchment paper and fill it with pie weights or dried beans. Bake for 15 minutes, then remove the weights and parchment, continuing to bake for an additional 5 minutes until the crust is lightly golden. Let it cool slightly while you prepare the custard.

In a medium saucepan, combine whole milk, heavy cream, ground cinnamon, and vanilla extract. Warm this mixture over medium heat, stirring gently until it begins to steam. Once steaming, remove it from heat and set it aside to let the spices steep.

In a mixing bowl, beat together eggs, granulated sugar, and a pinch of salt until the mixture is smooth and pale, about 2 minutes.

Gradually pour the warm milk mixture into the egg mixture, whisking continuously. Once combined, strain the custard through a fine-mesh sieve into a clean bowl.

Pour the custard mixture into your pre-baked pie crust, spreading it evenly. Reduce the oven temperature to 325°F (160°C) and bake for 35-40 minutes.

Once baked, allow the pie to cool at room temperature for 1 hour. After it has cooled, transfer it to the refrigerator to chill for at least 2 hours before serving.