In a bowl, whisk together flour and salt, then cut in cold butter until mixture resembles coarse crumbs.

Add ice water 1 tbsp at a time until dough just holds together. Form into a disk, wrap, and chill for 30 minutes.

Heat oven to 375°F (190°C).

Roll the chilled dough on a floured surface into a 10–11 inch circle.

Fit into a 9-inch pie dish, trim edges, line the crust with parchment, fill with pie weights or dried beans.

Blind bake at 375°F (190°C) for 12 minutes, then remove weights and parchment, and bake for an additional 5 minutes until lightly golden. Let cool slightly.

In a medium saucepan, heat milk over medium heat until it's warm and steaming but not boiling (about 170°F / 77°C). Remove from heat.

In a large bowl, whisk together eggs, sugar, cornstarch, cinnamon, and salt until smooth.

Slowly whisk in the warm milk a little at a time to temper the eggs and prevent scrambling. Stir in vanilla extract.

Pour the mixture back into the saucepan and cook on low-medium heat, stirring constantly until it thickens and coats the back of a spoon (about 5–8 minutes). Optionally strain through a fine-mesh sieve for extra-silky texture.

Pour the warm custard into the pre-baked crust, smoothing the top with a spatula.

Lower oven to 325°F (160°C). Bake the filled pie for 35–40 minutes, until the edges are set and the center is slightly wobbly.

Cool the pie on a wire rack for 30–60 minutes, then refrigerate for at least 2 hours (best if chilled for 4 hours) before serving.

Slice with a sharp knife (wipe between cuts for clean slices). Top with whipped cream, toasted nuts, or fruit if desired.