01 - Whisk flour, salt, and sugar in a mixing bowl. Cut in cold butter until the mixture forms coarse crumbs. Add ice water gradually, mixing just until dough forms. Shape into a disk, wrap, and chill for at least 1 hour.
02 - Set oven to 375°F (190°C).
03 - On a floured surface, roll the chilled dough to fit a 9-inch pie pan. Transfer and press gently in the pan. Trim and crimp the edges. Refrigerate for 15 minutes.
04 - Line crust with parchment and fill with pie weights or dried beans. Bake for 15 minutes. Remove weights and parchment. Bake an additional 8–10 minutes until lightly golden. Cool slightly.
05 - In a saucepan over medium heat, melt brown sugar and butter, stirring constantly until bubbly and slightly thickened, about 2–3 minutes. Remove from heat.
06 - Whisk cornstarch, cinnamon, ginger, nutmeg, salt, and eggs in a large bowl. Slowly whisk in milk and heavy cream. Incorporate pumpkin purée and vanilla extract. Gradually whisk in warm butterscotch mixture.
07 - Pour the filling into the pre-baked crust. Bake for 35–40 minutes until set at the edges and the center jiggles slightly. Cool to room temperature, then chill for at least 2 hours.
08 - Whip heavy cream, powdered sugar, and vanilla until soft peaks form using an electric mixer. Spread or pipe over the chilled pie.
09 - Slice and serve chilled.