Preheat oven to 400°F (204°C). Position oven rack to the middle low position. Line a large baking sheet with parchment paper or a silicone baking mat. Set aside.
Make the Scone Dough: In a large mixing bowl, whisk together the flour, baking powder, cinnamon, pumpkin pie spice, and salt.
Grate the frozen butter using the large holes of a box grater. Add the grated butter shreds to the flour mixture. Use a pastry cutter or your fingertips to gently toss and combine until the mixture resembles coarse, pea sized crumbs. Place the bowl in the refrigerator while you mix the wet ingredients.
In a separate small bowl or liquid measuring cup, whisk together ⅓ cup (75ml) of the heavy cream, the egg, blotted pumpkin puree, brown sugar, and vanilla extract until smooth.
Pour the wet ingredients over the chilled flour butter mixture. Fold together gently with a rubber spatula just until the dough appears moistened and begins to come together. Do not overmix.
With floured hands, gently work the dough into a ball inside the bowl. Transfer the dough to a lightly floured work surface. Press the dough into an even 8-inch disc. Using a very sharp knife or bench scraper, cut the disc into 8 equal wedges.
Arrange the scone wedges at least 2 inches apart on the prepared baking sheet.
Brush the tops of the scones evenly with the remaining 2 Tablespoons of heavy cream. Sprinkle generously with coarse sugar, if desired.
Bake for 20 to 25 minutes, or until the scones are lightly golden brown on top and around the edges.
Remove from the oven and allow scones to cool on the baking sheet for 5 minutes while you prepare the glaze.
Make the Glaze: In a small saucepan over low heat, combine the butter and maple syrup. Warm gently, whisking occasionally, just until the butter is completely melted. Remove the pan from the heat immediately. Whisk in the sifted confectioners' sugar until the glaze is completely smooth. Taste and add a small pinch of salt if desired.
Drizzle the warm maple glaze generously over the slightly cooled scones. Serve immediately.