Start by preheating your oven to 400°F and lining a large baking sheet with parchment paper. Set your bowl of dry ingredients aside so it's ready the moment your wet mixture is done. Getting this step done early keeps the whole process moving quickly.
Whisk together the flour, baking powder, cinnamon, pumpkin pie spice, and salt in a large bowl until fully combined. This ensures your leavening and spices are spread evenly, so you won't get any bland or overly spiced bites later on.
Grate the frozen butter directly into your flour mixture using a box grater. Toss it gently with your fingers or a pastry cutter until the mixture looks like coarse, pea-sized crumbs. This step is what gives the scones their signature flaky texture.
In a separate bowl, whisk together the heavy cream, buttermilk, blotted pumpkin puree, brown sugar, and vanilla extract. Make sure everything is fully blended before you pour it into the dry mixture, so you don't end up with pockets of unmixed pumpkin.
Pour the wet mixture into the dry ingredients and gently fold everything together just until it comes together. Turn the shaggy dough out onto a floured surface and pat it into a circle about an inch thick, then slice it into eight wedges.
Arrange the wedges on your prepared baking sheet, leaving space between each one. Bake for 22 to 25 minutes, or until the edges turn golden brown and the tops are lightly browned.
Let the scones cool for a few minutes on a wire rack before whisking together your powdered sugar and maple syrup. Drizzle the glaze generously over the top and let it set for a few minutes before serving warm.