Preheat oven to 400 degrees. Line a baking sheet with parchment paper or a silicone baking mat. Set aside.
In a large bowl, combine flour, brown sugar, cinnamon, baking powder, pumpkin pie spice, baking soda and salt. Add frozen grated butter and toss with the dry ingredients.
In another large bowl, whisk together pumpkin puree, milk, egg and vanilla. Pour mixture over dry ingredients and stir using a wooden spoon until a soft dough forms.
On a lightly floured surface, knead the dough a couple of times until it comes together.
Place dough on your prepared baking sheet and pat out to an 8-inch circle. Using a pizza cutter or a sharp knife, cut 8 even wedges from the circle. Separate wedges on baking sheet.
Place baking sheet into oven and bake for 12 - 15 minutes, or until a toothpick inserted in the center comes out clean.
Remove scones from baking sheet to wire rack to cool completely before glazing.