Cook onion and leek in oil in large pot, covered, until softened, about 5 minutes. For Spice Sachet: Wrap cinnamon, garlic, cloves, bay leaf and peppercorns in cheesecloth.
Add squash, sweet potatoes, spice sachet and broth to pot. Cook, covered, 15 minutes. Uncover; cook 45 minutes or until squash is cooked through.
Remove spice sachet. Working in batches, puree soup in blender. Return to pot. Stir in cream, butter, salt and pepper. Gently heat through.
Serve in warm soup plates or bowls, topped with smoked pheasant, if desired, and sprinkled with parsley. Makes 6 servings.