Step 1: Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Step 2: In a large mixing bowl, whisk together the flour, brown sugar, baking powder, pumpkin pie spice, and salt until well combined.
Step 3: Add the cold, grated butter to the flour mixture. Use a pastry cutter or two forks to cut the butter into the flour until it resembles coarse crumbs with some pea-sized pieces remaining.
Step 4: In a separate small bowl, whisk together the pumpkin puree, egg, heavy cream, and vanilla extract.
Step 5: Pour the wet ingredients into the dry ingredients. Gently fold with a spatula until a shaggy dough begins to form. Do not overmix.
Step 6: Turn the dough onto a lightly floured surface. Gently knead it 3-4 times just until it comes together. Pat the dough into a circle about 8 inches in diameter and 1 inch thick.
Step 7: Using a sharp knife or bench scraper, cut the circle into 8 even wedges. Place the wedges on the prepared baking sheet, leaving space between them.
Step 8: Optional: Chill the scones in the freezer for 10 minutes before baking to ensure maximum flakiness.
Step 9: Bake for 18-22 minutes, or until the scones are lightly browned on the edges and a toothpick inserted into the center comes out clean.
Step 10: While the scones cool, prepare the glaze by whisking together the powdered sugar, maple syrup, and milk until smooth. Drizzle over the slightly cooled scones and serve.