In a food processor, pulse together the flour blend, cornstarch, salt, and sugar. Add cold butter and pulse until crumbly with pea-sized bits. Mix in egg yolk and drizzle in ice water a spoonful at a time until the dough holds when pinched. Form into a disk, wrap, and chill for at least 1 hour.

Preheat oven to 375°F (190°C). Roll dough between parchment into a 12-inch circle and transfer to a 9-inch pie dish. Trim and crimp edges, then chill for 15 minutes. Prick base with a fork, line with parchment, and fill with pie weights. Bake 18 minutes, remove weights, and bake 7–10 minutes more until lightly golden. Cool slightly.

Heat cream until steaming, then pour over chopped chocolate and butter in a bowl. Let sit for 1 minute, then stir until smooth. Spread evenly over crust and chill 10–15 minutes to set.

Whisk pumpkin, eggs, brown sugar, maple syrup, cinnamon, ginger, and salt in a large bowl. Whisk in half-and-half until smooth.

Lower oven to 350°F (175°C). Pour filling over set ganache. Optionally swirl in a spoonful of ganache for decoration. Bake 45–55 minutes, until edges are set and center has a gentle jiggle.

Cool completely at room temperature, then refrigerate for at least 2 hours or overnight. Slice neatly and top with whipped cream or chocolate curls.