Line a baking sheet with parchment paper.
Whisk flour, sugar, baking powder, salt, and 2 teaspoons pumpkin pie spice, then cut in cold butter until crumbly.
Whisk pumpkin puree, 6 tablespoons cream, egg, and vanilla, then stir into the dry mix until a rough dough forms.
Knead gently, pat into a 1-inch circle, cut into 12 wedges, and chill 30 minutes.
Preheat oven to 375°F.
Brush chilled wedges with cream and sprinkle with remaining spice.
Bake 22-25 minutes until golden, cool 5 minutes on the pan, then move to a rack.
Whisk confectioners' sugar, 3 tablespoons cream, and vanilla into a thick glaze.
Drizzle over cooled scones and let set 10 minutes before serving.