Preheat the oven to 350°F.
Line a baking sheet with parchment paper.
In a medium bowl, whisk together flour, baking powder, salt, and pumpkin pie spice; set aside.
In a large bowl, whisk the eggs, brown sugar, pumpkin and vanilla on medium speed with a stand mixer or hand mixer until the mixture thickens, about 2 to 3 minutes.
Stir the flour mixture into the egg mixture, then mix in the pecans (mixture will be crumbly).
On a lightly floured work surface, divide the dough in half. Shape each half into a 3x10 inch log. Set the logs lengthwise on the prepared baking sheet, evenly spacing them apart.
Dampen your hands and smooth the surface of the logs.
Bake until the logs are slightly firm to the touch, about 25-30 minutes.
Remove the baking sheet from the oven and decrease the oven temperature to 300°F . Let the logs cool on the baking sheet for 15 minutes.
Transfer the logs to a cutting board. With a serrated bread knife, cut each log diagonally into slices ½ inch thick.
Place the cookies, cut sides up, in a single layer on the baking sheet. Bake until the biscotti are firm, about 20 minutes, flipping them midway through baking. Let cool completely.
Once the biscotti is completely cool, dip or drizzle with white chocolate.