In a large mixing bowl, combine the all-purpose flour, brown sugar, baking powder, cinnamon, pumpkin pie spice, and salt. Mix thoroughly using a whisk to evenly distribute the dry ingredients. Using a pastry cutter or fork, cut in the butter until the mixture resembles coarse crumbs, with pieces of butter about the size of lentils remaining visible for a flaky texture.
In a separate bowl, whisk together the pumpkin puree, egg, vanilla extract, and heavy cream until smooth. Gradually fold the wet mixture into the dry ingredients, stirring gently until a soft dough begins to form. Avoid overmixing to maintain a tender texture.
Turn the dough out onto the prepared parchment paper. Shape it into a circle with your hands, patting it gently to create an 8-inch disk. If the dough feels sticky, dust it lightly with flour until manageable. Use a sharp knife or bench scraper to divide the circle into 8 equal wedges. Gently separate the wedges slightly to allow room for baking.
Place the tray with the scones into the freezer for at least 30 minutes to help firm them up and relax the gluten. Meanwhile, preheat your oven to 400°F (200°C).
Once the scones have chilled, remove them from the freezer. Brush the tops with a little heavy cream and sprinkle with turbinado sugar for added crunch and sweetness. Bake for 25-28 minutes, or until the scones are golden brown and a toothpick inserted in the center comes out clean.