For the puree: For the easiest reliable route, use good tinned pumpkin. To make Gordon's from scratch, halve a 700g piece of pumpkin, scoop out the seeds, drizzle with oil and roast at 180C (160C fan, 350F) cut-side down for about an hour until soft. Scoop out the flesh and blend until completely smooth, then drain off any watery liquid so the filling sets firm.
Blind bake: Roll the pastry and line a 23cm tart tin. Line with foil and baking beans, bake at 190C (170C fan, 375F) for 15 minutes. Lift out the foil and beans, prick the base all over with a fork, and bake 5 minutes more until just starting to colour. Brush the base with egg white and give it 2 final minutes to seal. Drop the oven to 160C (140C fan, 325F).
Mix the filling: Whisk the puree with the brown sugar, cream, eggs, yolk, cornflour, spices and vanilla until smooth, taking care not to whip in air.
Bake: Pour into the warm shell. Bake 40 to 50 minutes, until set at the edges with a slight wobble in the middle.
Cool slowly: Turn the oven off and leave the pie inside to cool, then chill. It carries on setting as it cools, so don't rush it.
Serve: Serve at room temperature or cold, with lightly whipped cream.
