If you haven't yet, place the butter in the freezer.**
Heat oven to 400°. Line a baking sheet with a Silpat or parchment.
In a large bowl, whisk together flour, baking powder, spices, and salt.
Remove the butter from the freezer and grate it over the dry ingredients using the large holes of a box grater.
Using a pastry cutter, roughly cut in the butter curls. The main goal is getting the butter evenly tossed with flour and breaking up very large clumps. There should still be visible pieces of butter throughout.
Measure pumpkin into a glass measuring cup. Blot with a paper towel, pressing and holding until the towel is nearly soaked through.
Add ¼ cup cream, brown sugar, and vanilla to the measuring cup with the pumpkin and stir until well mixed.
Pour the pumpkin mixture into the dry ingredients. Stir gently about 20 times. There will still be bits of dry, flour visible in the bowl.
Dump the contents of the bowl onto a clean work surface. Knead the shaggy bits of flour into the dough, folding 8-10 times until it comes together in a neat disk. This folding process is what produces flaky layers in the scones!
Cut the disk into 8 triangles. Place 2" apart on the prepared baking sheet.
If desired, brush the tops of the scones with the last tablespoon of cream and sprinkle with raw sugar.
Bake for 16-20 minutes, until the tops are golden and the scones do not squish if you gently press on the center.
Cool at least 5 minutes before serving.