In a large bowl, whisk together flour and salt. Cut in the cold butter using a pastry blender or your fingertips until the mixture resembles coarse crumbs.
Gradually add cold water, 1 tablespoon at a time, mixing until the dough just comes together. Do not overmix. Form the dough into a disc, wrap in plastic wrap, and refrigerate for at least 30 minutes.
Preheat oven to 400°F (200°C). On a lightly floured surface, roll out the dough into a 12-inch circle. Carefully transfer the dough to a 9-inch pie plate. Crimp the edges as desired.
In a separate bowl, whisk together eggs, sugar, heavy cream, milk, vanilla extract, and cinnamon until well combined.
Pour the filling into the prepared pie crust.
Bake for 15 minutes at 400°F (200°C). Then, reduce the oven temperature to 350°F (175°C) and bake for an additional 30-35 minutes, or until the center is set and a knife inserted near the center comes out clean.
Let the pie cool completely on a wire rack before slicing and serving.
Notes
This pie can be served with a dollop of whipped cream or a scoop of vanilla ice cream.