Preheat your oven to 375°F (190°C). Prepare your pie crust in a 9-inch pie dish, ensuring it's evenly pressed into the edges. Line with parchment paper, fill with pie weights or dried beans, and bake for 15 minutes. Remove the weights and parchment, then return the crust to the oven for an additional 5 minutes or until it’s golden brown. Let it cool slightly.

In a medium saucepan, combine the whole milk and heavy cream over medium heat, adding the ground cinnamon and pure vanilla extract. Heat until steaming but do not boil. Remove from heat and set aside to cool slightly.

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

Slowly pour the warm cream mixture into the egg and sugar mixture, whisking continuously to temper the eggs. Strain through a fine mesh sieve into another bowl.

Reduce the oven temperature to 325°F (160°C). Pour the custard mixture into the pre-baked pie crust and bake for about 35-40 minutes. The edges should be set but the center still has a slight jiggle.

Once baked, let the pie cool at room temperature for about 30 minutes. Cover loosely with plastic wrap and refrigerate for at least 2 hours before slicing.