Preheat your oven to 425°F (220°C) and line a baking sheet with parchment paper.

In a large mixing bowl, whisk together flour, sugar, baking powder, salt, and pumpkin spice until well blended.

Grate the cold butter into the dry mixture, then gently toss until it resembles coarse crumbs.

In a separate bowl, whisk together pumpkin purée, half and half, and the large egg until smooth.

Pour the wet ingredients into the dry ingredients and mix gently until just combined. Shape the dough into a circle and cut into eight triangles.

Place the scones on the baking sheet and bake for approximately 15 minutes until golden brown on the edges.

Allow the scones to cool on a wire rack for a few minutes.

In a small bowl, mix powdered sugar and arrowroot powder (if using) with enough half and half to create a smooth glaze, then drizzle over the cooled scones.