Preheat your oven to 375°F (190°C). Roll out your pie crust on a floured surface to about 1/8 inch thick. Fit the crust into a 9-inch pie dish, trim excess edges, and line with parchment paper filled with pie weights. Blind-bake for 20 minutes until lightly golden, then remove weights and cool.

In a medium saucepan, combine whole milk and heavy cream with ground cinnamon and pure vanilla extract. Heat over low to medium until steaming but not boiling. If using, steep a cinnamon stick. Remove from heat and let cool for 10 minutes.

In a large bowl, whisk together eggs, granulated sugar, and a pinch of salt until pale and slightly thickened, about 2-3 minutes.

Gradually pour the warm cream mixture into the egg mixture while whisking vigorously to temper the eggs. Strain through a fine-mesh sieve into a clean bowl.

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

Let the pie cool at room temperature for about 30 minutes, then refrigerate for at least 2 hours or overnight.