Preheat the oven to 400°F. Line a baking sheet with parchment paper.
In a small bowl, whisk together the pumpkin, egg, half and half, and vanilla. Set aside.
In the bowl of a food processor, combine flour, brown sugar, baking powder, baking soda, salt and pumpkin pie spice. Pulse a few times to combine.
Cut cold butter into 1/2-inch chunks. Add to food processor and pulse until the mixture is crumbly with pea-size chunks of butter. Add pumpkin mixture and pulse just until the mixture comes together. (The dough will be very sticky.)
Turn dough out onto floured surface and dust the top lightly with more flour. Gently knead the dough until it comes together and pat into 8-inch circle. (If dough is still too sticky to work with add some additional flour.)
Using a knife dusted with flour, slice each circle into 8 wedges. Place the wedges on the prepared baking sheet.
Bake until golden brown and a wooden pick inserted in center comes out clean, about 15 minutes. Transfer to a wire rack to cool completely.
Drizzle with glaze and sprinkle with *toasted pecans.