Step 1 Adjust an oven rack to the lower middle position. Preheat the oven to 400°F. Stack two baking sheets on top of each other and line the top sheet with parchment paper.
Step 2 In a large bowl, whisk the flour, sugar, baking powder, cinnamon, ginger, nutmeg, and salt. In a medium bowl or liquid measuring cup, whisk the pumpkin puree, heavy cream, egg, egg yolk, and vanilla.
Step 3 Add the butter to the dry ingredients and use a pastry cutter to cut it into the mixture until the flour-coated pieces are the size of peas. Add the wet ingredients and fold with a spatula until just combined.
Step 4 Transfer the dough to a lightly floured surface, and knead until it comes together, 4 to 6 times, adding flour as necessary if the dough is sticky. Pat the dough gently into a small square and roll it into a 12-inch square (again, using flour as necessary). Fold the dough in thirds similar to a business letter. Fold the dough into thirds again, making a square. Transfer it to a floured sheet pan or plate and put it in the freezer for 10 minutes.
Step 5 Return the dough to the floured surface. Roll it into a 12-inch square and fold it business letter style. Place the dough seam side down and gently roll into a 12 by 4-inch rectangle. With a sharp knife (or bench scraper), cut the rectangle crosswise into 4 equal rectangles, then cut each rectangle diagonally into 2 triangles. Transfer the triangles to the prepared baking sheet.
Step 6 Brush the tops with a little heavy cream, making sure it doesn’t drip down the sides. Bake 18 to 25 minutes, rotating the pan halfway through, until the tops and bottoms are golden brown.
Step 7 Transfer the sheet pan to a wire rack and let the scones cool slightly. Top with the Maple Frosting.
Step 8 In a small bowl, whisk the maple syrup, confectioners’ sugar, vanilla, and salt until smooth.
