Preheat your oven to 375°F (190°C). Fit the pie crust into a 9-inch dish, line it with parchment paper, and weigh it down with pie weights or dried beans. Bake for 15 minutes, remove weights, and bake for another 5 minutes until golden. Let cool slightly.

In a medium saucepan, combine the whole milk and heavy cream with ground cinnamon and vanilla extract. Heat on medium until steaming, without boiling. If using whole spices, steep for about 10 minutes. Remove from heat.

In a large mixing bowl, whisk together the fresh eggs, granulated sugar, and a pinch of salt until pale and smooth, about 2-3 minutes.

Gradually pour the hot milk and cream mixture into the egg mixture while continuously whisking to prevent curdling. Strain the custard through a fine-mesh sieve.

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

Allow the pie to cool to room temperature, then refrigerate for at least 2 hours before serving to let the custard set.