Preheat your oven to 375°F (190°C). Place your pie crust into a 9-inch pie dish. Line the crust with parchment paper, fill with baking weights or dried beans, and bake for 15 minutes. Remove the weights and parchment, then bake for another 5 minutes, until lightly golden. Let it cool slightly on a wire rack.

While the crust cools, combine the whole milk, heavy cream, ground cinnamon, and pure vanilla extract in a medium saucepan. Heat over medium heat, stirring occasionally, until steaming and tiny bubbles begin to form. Do not let it boil. If using a cinnamon stick or vanilla bean, steep for 10 minutes before discarding.

In a large mixing bowl, whisk together the eggs, granulated sugar, and a pinch of salt until smooth, pale, and slightly thickened.

Slowly pour about half of the hot milk mixture into the egg mixture while continuously whisking to temper the eggs. Once combined, pour the tempered egg mixture back into the remaining hot milk mixture in the saucepan, whisking constantly until fully incorporated. Strain the mixture through a fine-mesh sieve into a clean bowl for a smoother custard.

Reduce the oven temperature to 325°F (160°C). Carefully pour the strained custard base into the pre-baked pie crust. Bake for 35–40 minutes, until the edges are set and firm, but the center has a slight jiggle when nudged.

Remove the pie from the oven and let it cool completely at room temperature on a wire rack. Once cooled, cover loosely and refrigerate for at least 2 hours before slicing and serving.