Preheat the oven to 400°F (200°C).
Wash and dry the sweet potatoes.
Prick each potato with a fork several times.
Place on a baking sheet and roast for 45–55 minutes or until very soft.
Let cool, remove skins, and mash until smooth.
Combine flour and salt in a bowl.
Add chilled butter and cut it in using a pastry cutter until the mixture resembles coarse crumbs.
Add ice water, one tablespoon at a time, mixing just until the dough holds together.
Gently shape into a disk, wrap, and chill for 30 minutes.
Roll out on a floured surface and fit into a 9-inch pie dish.
In a large bowl, mix the mashed sweet potatoes and melted butter.
Add sugars and combine until smooth.
Whisk in eggs one at a time.
Add evaporated milk, vanilla, cinnamon, nutmeg, ginger, and salt.
Whisk until silky and well combined.
Preheat the oven to 350°F (175°C).
Pour the filling into the unbaked pie crust.
Smooth the top.
Bake for 50–55 minutes or until the center is set but still slightly jiggly.
Cool completely before slicing to ensure clean cuts.
