01 - In a large bowl, combine flour, salt, and sugar. Cut in cold butter using a pastry cutter or fingertips until coarse crumbs form. Gradually add ice water, one tablespoon at a time, mixing until dough just holds together. Shape into a disk, wrap in plastic, and refrigerate at least 30 minutes.
02 - Set the oven to 375°F (190°C) to preheat.
03 - On a lightly floured surface, roll chilled dough to fit a 9-inch pie dish. Transfer gently, trim excess, crimp edges, and prick base with a fork. Place in refrigerator while preparing filling.
04 - Whisk together mashed sweet potatoes, brown sugar, eggs, evaporated milk, heavy cream, melted butter, and vanilla extract until smooth. Stir in cinnamon, ginger, nutmeg, allspice, and salt until evenly combined.
05 - Pour filling into the crust-lined pie plate, smoothing the surface evenly.
06 - Bake 55 to 60 minutes until filling is set but slightly wobbly at the center. Cover crust edges with foil if browning too quickly.
07 - Cool completely on a wire rack before slicing. Serve at room temperature or chilled.