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

In a medium saucepan, combine whole milk, heavy cream, ground cinnamon, and vanilla extract. Heat over medium-low until steaming, stirring frequently.

In a large bowl, whisk eggs, granulated sugar, and salt until pale and smooth. Set aside.

Slowly pour warm cream mixture into egg mixture while whisking to temper the eggs. Strain through a fine sieve.

Pour custard filling into cooled pie crust. Bake at 325°F (160°C) for 35-40 minutes until edges are set and the center jiggles slightly.

Cool the pie at room temperature, then chill in the refrigerator for at least 2 hours before slicing.