For crust: In the work bowl of a food processor, place flour, sugar, and salt; pulse until combined. Add cold butter, and pulse until mixture is crumbly. With processor running, add ¼ cup ice water in a slow, steady stream just until dough comes together. Turn out dough onto a lightly floured surface, and shape into a disk. Wrap in plastic wrap, and refrigerate for at least 1 hour.
Preheat oven to 350°. On a lightly floured surface, roll dough into a 12-inch circle. Transfer to a 9-inch pie plate, pressing into bottom and up sides. Fold edges under, and crimp as desired. Top with a piece of parchment paper, letting ends extend over edges of plate. Add pie weights.
Bake for 20 minutes. Carefully remove paper and weights. Let cool on a wire rack for 20 minutes.
For filling: In a large bowl, whisk together brown sugar, pumpkin pie spice, flour, and salt. Add pumpkin, evaporated milk, melted butter, vanilla, and egg, whisking until combined. Pour into prepared crust.
Bake until filling is set, about 30 minutes.
For streusel: In a medium bowl, combine flour, pecans, brown sugar, pumpkin pie spice, baking powder, and salt. Add melted butter, tossing with a fork until crumbly. Sprinkle over pie. Bake until streusel is lightly browned, about 20 minutes more. Let cool completely on a wire rack. Serve with whipped cream, if desired.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/pumpkin-streusel-pie/