Make the Crust: In a large bowl, whisk together the flour and salt. Cut in the butter and shortening using a pastry blender or your fingers until the mixture resembles coarse crumbs. Gradually add the ice water, one tablespoon at a time, mixing until the dough just comes together. Form the dough into a disc, wrap in plastic wrap, and chill for at least 30 minutes.

Prebake the Crust: On a lightly floured surface, roll out the dough into a 12-inch circle. Transfer to a 9-inch pie plate. Trim and crimp the edges. Prick the bottom of the crust with a fork. Line the crust with parchment paper and fill with pie weights or dried beans. Bake in a preheated oven at 375°F (190°C) for 15 minutes. Remove the parchment paper and pie weights and bake for another 5-10 minutes, or until lightly golden brown. Let cool completely.

Make the Filling: In a large bowl, whisk together the pumpkin puree, evaporated milk, eggs, granulated sugar, brown sugar, pumpkin pie spice, salt, and vanilla extract until smooth.

Bake the Pie: Pour the filling into the prebaked crust. Bake in a preheated oven at 350°F (175°C) for 50-60 minutes, or until the filling is set around the edges but still slightly wobbly in the center.

Cool and Chill: Let the pie cool completely on a wire rack. Then, cover and chill in the refrigerator for at least 4 hours before serving.