Preheat the oven to 400°F and set the rack in the center. Line a baking sheet with parchment paper and set aside.
In a large mixing bowl combine the flour, brown sugar, baking powder, salt, cinnamon, ground ginger, nutmeg, cloves, and allspice. Add cold butter cubes to the flour mixture and work the butter into the flour mixture, using your fingers or a pastry cutter, until the mixture resembles coarse pea or dime-size crumbs. Be careful not to overwork the mixture or the butter will soften too much and the resulting scones will not be flaky. Add the pecans and toss well.
Stir together the pumpkin puree, egg, and a couple tablespoons of milk. Add it to the flour mixture and mix until just combined, kneading lightly (but don’t overwork it). Add more milk if needed to create a soft, slightly sticky dough.
Scrape dough onto a nicely floured large wooden cutting board or work surface. The dough may be sticky, so take extra care flouring your hands and the sides and top of the dough as well. Divide the dough in half and pat each portion into a ¾-to-1-inch thick circle. Don’t overwork the dough, as you want the butter inside to stay as cold as possible until the scones head into the oven.
Use a bench/dough scraper or knife to cut 6 wedges (like a pizza) from each round. Flip each cut scone over and place upside down on the parchment lined baking sheet (the bottoms are flatter and will look prettier as the tops of the scones), spacing a couple inches apart. Lightly brush on top of the scones (but not the sides) with a little milk or heavy cream. Bake scones for 15 to 20 minutes until lightly golden on top. Remove from the oven and allow the scones to cool on the pan while you prepare the glaze.
Stir together the confectioners’ sugar, milk, and maple syrup until smooth. If the glaze is too thin, add a sprinkle more confectioners’ sugar. Too thick, add a drizzle of milk. When scones are cool, drizzle the glaze over the tops. Allow the glaze to set briefly and then serve the scones at room temperature.