Preheat your oven to 375°F (190°C). Roll out your pie crust into a 9-inch pie dish, fill with parchment and weights, then blind bake for 15 minutes. Remove weights, bake uncovered for another 5 minutes until golden. Cool crust.

Combine whole milk, heavy cream, ground cinnamon, and vanilla extract in a saucepan. Heat over medium until steaming. Remove from heat and cool slightly.

Whisk together the eggs and sugar in a mixing bowl until pale and slightly thickened, about 2-3 minutes.

Slowly pour the warm milk mixture into the egg mixture while whisking constantly to temper. Strain through a sieve into a clean bowl.

Reduce oven temperature to 325°F (160°C). Pour custard into the pre-baked crust and bake for 35-40 minutes until edges are set but center jiggles slightly. Cool at room temperature for 30 minutes.

Transfer pie to the refrigerator and chill for at least 2 hours before serving to ensure it sets.