Preheat the oven to 375°F (190°C). Fit the pie crust into a 9-inch pie dish and blind bake it with weights for 15 minutes. Remove weights and parchment, bake for another 5 minutes until golden.

In a medium saucepan, combine the milk, cream, cinnamon, and vanilla. Heat until steaming but do not boil. If using whole spices, steep and then strain.

Whisk together the eggs, sugar, and salt in a large bowl until pale and smooth.

Temper the eggs by slowly adding the hot milk mixture while whisking continuously. Strain the custard through a fine-mesh sieve into a bowl.

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

Allow the pie to cool at room temperature for 30 minutes, then refrigerate for at least 2 hours before serving.