Preheat your oven to 375°F (190°C). Roll out your pie crust into a 9-inch pie dish, line it with parchment paper, fill with weights, and bake for 15 minutes. Remove weights and bake for another 5 minutes until golden brown. Cool while preparing custard.

In a medium saucepan, combine whole milk, heavy cream, cinnamon, and vanilla. Heat gently over medium heat until it steams, then let steep for 10 minutes. Remove from heat and let cool slightly.

In a mixing bowl, whisk together eggs and granulated sugar until pale and slightly thickened, about 3 minutes.

Slowly pour warm milk mixture into the egg-sugar mixture while whisking continuously. Strain through a fine-mesh sieve into a clean bowl.

Reduce oven temperature to 325°F (160°C). Pour custard into pie crust, avoiding overfilling. Bake for 35 to 40 minutes, until edges set and center jiggles slightly.

Remove pie from oven, allow to cool at room temperature for 1 hour. Cover and refrigerate for at least 2 hours or overnight.