01 - Preheat oven to 350°F. Fit the unbaked pie crust into a 9-inch pie pan and crimp or trim edges as desired.
02 - In a medium saucepan, combine whole milk and heavy cream. Heat over medium until steaming but not boiling. Remove from heat.
03 - In a mixing bowl, whisk eggs, granulated sugar, cornstarch, vanilla extract, cinnamon, and salt until the mixture is smooth.
04 - Slowly pour the warm milk mixture into the egg mixture while whisking constantly until fully integrated.
05 - Pour the custard mixture through a fine-mesh sieve into a clean bowl to remove any lumps and create a silky texture.
06 - Pour the strained custard filling into the prepared pie crust. Bake for 45–50 minutes or until the center is just set but slightly wobbly. Shield crust edges with foil if browning quickly.
07 - Place baked pie on a wire rack to cool. The custard will continue to set as it cools to room temperature.
08 - Sprinkle with ground cinnamon and dust with powdered sugar if desired. Refrigerate for at least 2 hours before slicing.