1Cook bacon in large heavy pot over medium heat until bacon is crisp and fat is rendered, about 5 minutes. Remove bacon with slotted spoon to drain on paper towels. Leave fat in pot. crumble bacon and set aside.
2Saute' the onion, garlic, cinnamon, allspice, and ginger in bacon fat until tender, about 5 minutes. Season vegetables with salt and pepper. Stir in chicken broth and canned pumpkin, then add the sweet potatoes.
3reduce heat and simmer 15 minutes or until sweet potatoes are tender. Puree soup with immersion blender until smooth. Stir in heavy cream and cayenne. Serve with bacon crumbles and chives as garnish.