In a large mixing bowl, whisk together dry ingredients: flour, brown sugar, baking powder, pumpkin spice, cinnamon, and salt until combined.
Add cold butter and using a pastry blender, cut butter into the flour mixture until well blended – butter pieces should be about the size of peas.
Add pumpkin puree, buttermilk, and vanilla and gently stir until combined.
Sprinkle a little flour on the counter and dump out the scone batter onto the counter. Using your hands, pat the dough gently to form a rectangle about an inch thick. Cut into 12 pieces of equal size; I usually do triangles.
Place cut scones onto sheet pans lined with parchment paper or silicone mats.
Refrigerate for about 15 minutes while you preheat the oven to 425°F.
Bake scones for 15-20 minutes or until tops and bottoms of scones are lightly golden brown.
While the scones cool, make the espresso glaze.
In a small bowl, add icing sugar and vanilla. In a small dish, mix buttermilk with espresso powder until powder has completely dissolved, then add to the icing sugar mixture.
Whisk or stir until glaze is smooth and pourable.
Using a spoon, pour glaze over each scone. (see notes)
Scones will keep for up to 3 days in a sealed container.