In a medium bowl, whisk together the pumpkin and cream. Stir into the dry mixture just until mixed, then add walnuts. Spread a little flour on the counter, then scrape the dough out onto the flour. Form into a round, and flatten to about an inch thick. Sprinkle with chopped thyme, top with remaining Parmesan, and pat down with your palms. Using a knife, divide the round into 8 wedges. Transfer to the baking sheet, leaving a couple of inches between the scones.