In a large bowl, whisk together the flour, salt, and sugar. Using a pastry cutter or your fingertips, work the cold cubed butter into the flour mixture until it resembles coarse crumbs with some pea-sized pieces remaining.
Gradually add the ice water, 1 tablespoon at a time, mixing gently until the dough just comes together. Form into a disk, wrap in plastic, and refrigerate for at least 30 minutes.
Once chilled, place the dough on a lightly floured surface and roll it out to about ⅛-inch thickness, creating a circle approximately 12 inches in diameter.
Carefully transfer the dough to a 9-inch pie plate, gently pressing it into the bottom and sides. Trim any excess dough, leaving about a ½-inch overhang, then fold and crimp the edges decoratively. Return the pie shell to the refrigerator while preparing the fillings.
Preheat your oven to 375°F (190°C). In a medium bowl, whisk together the pumpkin puree, granulated sugar, eggs, vanilla extract, salt, and pumpkin pie spice until smooth and well combined.
Gradually stir in the evaporated milk until the mixture is silky and uniform.
In a separate bowl, combine the melted butter, brown sugar, cinnamon, flour, and vanilla extract. Stir until the mixture becomes a smooth, caramel-like paste.
Pour the pumpkin filling into the chilled pie crust.
Drop spoonfuls of the cinnamon swirl mixture over the top of the filling. Using a knife or a thin skewer, gently swirl the cinnamon mixture into the pumpkin filling, creating a beautiful marbled effect. Avoid over-mixing—you want distinct swirls rather than a uniform blend.
Place the pie on a baking sheet (to catch any potential overflow) and bake at 375°F for 50-60 minutes, or until the center is almost set but still slightly jiggly. The edges should be set, and a knife inserted about 1 inch from the edge should come out clean.
If the crust edges brown too quickly, shield them with aluminum foil or a pie crust shield after about 30 minutes of baking.
Allow the pie to cool completely on a wire rack for at least 2 hours before serving. This cooling period is crucial—it allows the filling to set properly and the flavors to meld together perfectly.
For the cleanest slices, consider refrigerating the pie for 1-2 hours after it reaches room temperature.