Preheat oven to 425 degrees then line a baking sheet with parchment paper and set aside. In the bowl of a large food processor (or in a large bowl) combine the flour, sugar, baking powder, salt, cinnamon, nutmeg, cloves, and ginger. Pulse or whisk to combine. Add cold butter and pulse until well incorporated and mixture is the texture of cornmeal. Alternatively, use your fingertips or a pastry butter to blend butter in. In a separate bowl, whisk together pumpkin puree, half & half, and egg. Add to flour mixture and pulse until just combined. Alternatively, stir until the dough comes together in a ball. Turn the dough out onto a lightly floured surface and gently knead 4 or 5 times to bring the dough together, then flatten into a circle 1" thick. Using a pizza cutter, cut the dough in half, then cut each half into thirds. Place the wedges onto the prepared baking sheet and bake for 14-16 minutes, or until just starting to turn golden brown. Remove to a cooling rack to cool completely. When scones are cool, whisk together the plain glaze ingredients, then spoon on top and spread slightly. Let harden for 10 minutes, then whisk together the spiced drizzle ingredients and drizzle on top. Let harden completely, about 1 hour, before serving. Store in an air-tight container for 1 day.