Preheat oven to 375°F (190°C). Roll out pie crust into a 9-inch pie dish, line with parchment paper, fill with weights, and bake for 15 minutes. Remove weights and parchment, bake for additional 5 minutes until golden. Allow to cool.

In a medium saucepan, combine whole milk, heavy cream, ground cinnamon, and pure vanilla extract over medium heat. Heat until steaming but not boiling. If using, steep a cinnamon stick in it for 10 minutes off the heat. Remove from heat and cool slightly.

In a mixing bowl, combine large eggs, granulated sugar, and a pinch of salt. Whisk until smooth and lighter in color, about 2-3 minutes.

Gradually pour the warm milk and cream mixture into the egg mixture while whisking continuously. Strain through a fine-mesh sieve into a clean bowl.

Lower oven temperature to 325°F (160°C). Pour custard filling into the pre-baked pie crust. Bake for approximately 35-40 minutes until edges are set and center jiggles slightly.

Cool pie at room temperature for at least 30 minutes, then refrigerate for a minimum of 2 hours to set.