Line a large baking sheet with parchment paper and set aside.
In a medium bowl combine pumpkin puree, brown sugar, egg, heavy cream and vanilla; set aside.
In a large bowl whisk together the flour, baking powder, baking soda and pumpkin pie spice.
Cut the cold butter into the flour using a pastry cutter or a fork, until the butter is well incorporated into the dry ingredients, and is pea-sized.
Pour the wet ingredients in and gently mix until it is almost all combined. Dump the mixture onto a floured work surface. Use your hands and gently bring the dough together. Pat it down and fold the dough over itself.
Gently pat the dough down and form it into a circular shape that is about 1-inch thick. Slice the dough into 8 triangular pieces and place them on the prepared baking sheet. Place the baking sheet into the freezer while the oven preheats. This will make sure we get flaky layers.
Preheat an oven to 375°F. Bake the scones for 20 - 22 minutes, or until the scones have puffed up and are firm to the touch. Do not let the tops brown as you don't want a dry scone. Let the scones cool on the pan for 10 minutes and then transfer them to a wire rack to cool completely.
While the scones are cooling, prepare the icing. Combine the confectioner's sugar and pumpkin pie spice in a small bowl. Add the milk, a little bit at a time, until a thick glaze forms.
Transfer the glaze to a small piping bag, or into a zip lock bag and snip off the end. Pipe the glaze onto the cooled scones to create a zigzag pattern. You can also use a spoon to drizzle on the icing. Let the glaze harden for 15 minutes before serving.