Sift the flour, sugar, baking powder and spices into a bowl and set aside. Whisk together the pumpkin puree, egg and heavy cream and set aside. Add the cold cubed butter to the dry ingredients and mix together with your fingertips until the butter is pea-sized. Add the wet ingredients and mix until just combined, making sure not to overwork the dough. On a work surface, pat the dough into a circle about 2 inches thick and cut out six equal wedges. Place on a baking sheet covered with parchment and brush the tops with heavy cream. Bake in a 350 degree oven for about 20 minutes, turning once during baking. Cool on a wire rack. Once the scones are cool, ice the scones with the vanilla icing first, then drizzle the cinnamon icing on top. Scones are best enjoyed fresh baked but will keep in an airtight container at room temperature for up to 3 days.
Mix together sugar, milk and vanilla until smooth. Reserve a 1/4 of the icing, mix with cinnamon powder and set aside. Ice the scones with a layer of the vanilla icing first, then drizzle the cinnamon icing on top.