In a large bowl, whisk the flour, sugar, and salt together.
1¼ cups all-purpose flour, 1 teaspoon granulated sugar, ½ teaspoon kosher salt
Add in the butter and shortening, and a pastry cutter or two forks to combine the ingredients until the butter and shortening are pea-sized pieces or smaller.
¼ cup unsalted butter, ¼ cup vegetable shortening
Add in 2 tablespoons of the water and stir until combined. Add the remaining tablespoons, one at a time, until the dough is crumbly, but begins to come together.
¼ cup ice water
Use your hands to gently knead the dough a few times until it comes together.
Turn the dough out onto a piece of plastic wrap and form it into a disc. Wrap tightly and refrigerate for 1 hour.
While the dough chills, preheat oven to 425°F. Cut the sweet potatoes in half lengthwise and prick the skin all over. Place them cut-side-down on a parchment-lined baking sheet. Bake until the sweet potatoes are tender all the way through, about 45 minutes.
1¼ pounds sweet potatoes
Spray a 9-inch pie plate with nonstick spray.
On a floured work surface, roll the chilled pie crust into a 12-inch circle. Transfer it to the pie plate and trim off any excess. Fold the edge of the crust under and use your finger and thumb to shape the crust. Refrigerate while you prepare the filling.
Once the sweet potatoes are cool enough to touch, scoop out the flesh and add it to a large bowl. Mash it until it is smooth.
Whisk in the eggs until combined.
2 large eggs
Whisk in the brown sugar, sugar, evaporated milk, vanilla extract, cinnamon, nutmeg, and salt until smooth.
½ cup brown sugar, ½ cup granulated sugar, 12 ounces evaporated milk, 1 teaspoon pure vanilla extract, ½ teaspoon ground cinnamon, ½ teaspoon ground nutmeg, ⅛ teaspoon kosher salt
Pour the filling into the crust and bake for 15 minutes at 425°F.
Lower the oven temperature to 350°F and bake for 35-40 minutes, until the crust is golden, the edges of the pie are set, and the center is only slightly jiggly.
Let cool completely at room temperature then cover and chill for 2-3 hours before serving.