To prepare a whole roasted chicken pumpkin dressing recipe, you will first need to prepare the roasting chicken. Wash the chicken and pat it dry with paper towels. Cut the breasts in half lengthwise and remove the bones. Place the skin side down on the baking sheet and roast for 20 minutes at 375 degrees F. Remove from the oven and allow to cool for 10 minutes before slicing. To make the dressing, combine the pumpkin puree, sugar, cinnamon, salt, and nutmeg. Whisk the ingredients together until the sugar dissolves. Pour the mixture into the prepared baking dish. Bake for 30 minutes or until chicken is no longer pink in the center and the juices run clear. Serve warm.