01 - Preheat oven to 350°F (175°C). Fit the unbaked pie crust into a 9-inch pie pan and crimp or trim edges as desired.
02 - Combine whole milk and heavy cream in a medium saucepan. Gently heat over medium until steaming, avoiding boiling. Remove from heat.
03 - In a mixing bowl, whisk eggs, granulated sugar, cornstarch, vanilla extract, ground cinnamon, and sea salt until homogenous.
04 - Gradually pour the warm milk mixture into the egg mixture while whisking continuously, ensuring even incorporation.
05 - Strain the blended custard through a fine-mesh sieve into a clean bowl for silky consistency.
06 - Pour custard filling into the prepared pie crust, tapping gently to release air bubbles.
07 - Bake for 45 to 50 minutes, until the center is set but still slightly wobbly. Tent pie edges with foil if crust browns too quickly.
08 - Remove pie from oven and let cool on a wire rack. The custard will firm as it cools.
09 - Sprinkle with ground cinnamon and dust with powdered sugar as desired just before serving.
10 - Refrigerate for a minimum of 2 hours before slicing for best texture.