In a mixing bowl, whisk together all-purpose flour and salt until combined. Cut the cold, cubed unsalted butter into the flour mixture using a pastry cutter until it resembles coarse crumbs. Gradually add ice water, one tablespoon at a time, mixing until the dough holds together. Form into a disc, wrap in plastic, and chill in the refrigerator for 30 minutes.

Preheat your oven to 375°F (190°C). On a floured surface, roll out the chilled dough into a circle about 12 inches in diameter. Carefully fit the dough into a 9-inch pie dish, trimming any excess. Prick the bottom with a fork to prevent bubbling, then place parchment paper on top and fill with pie weights. Blind bake for 15 minutes, remove weights, and bake for an additional 5-7 minutes until golden brown. Allow the crust to cool.

In a saucepan, heat whole milk over medium heat until steaming but not boiling. In a separate bowl, whisk together large eggs, granulated sugar, cornstarch, and pure vanilla extract until smooth. Ensure your mixing bowl is stable by placing it on a damp cloth to prevent slipping.

Gradually pour the steaming milk into the egg mixture while whisking continuously to temper the eggs. This gradual warming will prevent curdling. Once combined, return the mixture to the saucepan over low heat. Stir constantly with a wooden spoon for 8-10 minutes until the custard thickens and coats the back of the spoon.

Remove the saucepan from heat and stir in cold cubed butter and ground cinnamon until completely melted and incorporated. The creamy cinnamon-vanilla custard should be smooth and fragrant, giving a warm essence of holiday spices that will charm your guests.

To achieve the silkiest texture for your creamy cinnamon-vanilla custard pie, pass the custard through a fine-mesh sieve into a clean bowl. This step will catch any impurities or lumps, ensuring a velvety custard that sets beautifully.

Carefully pour the strained custard into the cooled pie crust. Make sure to fill it to just below the rim for a perfect presentation. Smooth the top with a spatula if necessary, then prepare for the second baking.

Lower the oven temperature to 325°F (160°C) and bake the filled pie for 30-35 minutes. Look for the edges of the custard to be set while the center still has a slight jiggle. This subtle movement indicates a perfect creamy texture once it cools.

After baking, let the pie cool at room temperature for 1 hour. This gradual cooling allows the flavors to meld beautifully. Then transfer the pie to the refrigerator and chill for at least 4 hours, preferably overnight, to achieve the best texture and taste.

When ready to serve your stunning creamy cinnamon-vanilla custard pie, top with a dollop of fresh whipped cream and a light sprinkle of cinnamon for an elegant finish. This delightful touch complements the flavors and invites everyone to indulge in the festive spirit.