Preheat the oven to 375°F (190°C). Roll out the crust and place it in a 9-inch pie dish. Line with parchment paper, fill with baking weights, and bake for 15 minutes. Remove weights and parchment, and bake another 5 minutes until lightly golden. Cool slightly.
Preparation of Custard Base
In a saucepan, heat milk and cream with cinnamon and vanilla until steaming (do not boil). If using a cinnamon stick or vanilla bean, steep for 10 minutes and remove.
In a mixing bowl, whisk eggs, sugar, and a pinch of salt until smooth and pale.
Slowly pour the hot milk mixture into the eggs while whisking constantly to temper. Strain through a fine-mesh sieve for extra smoothness.
Baking and Cooling
Lower the oven temperature to 325°F (160°C). Pour custard into the pie crust. Bake for 35–40 minutes until edges are set but the center still jiggles slightly.
Cool at room temperature, then refrigerate for at least 2 hours before slicing.
Slice with a sharp knife after chilling. Serve cold or slightly chilled. Top with a light dusting of cinnamon, a pinch of nutmeg, or a little whipped cream. Add a sprinkle of orange zest for bright holiday flavor. Store cover the pie with plastic wrap or place in an airtight container. Keep in the fridge up to 4 days. Do not freeze the baked custard pie; the texture will change.