Heat oil in a heavy-bottom pot. Add leeks, onion, celery, carrot, sweet potatoes, pumpkin, and garlic, and saute until they start to brown.
Add bay leaf, stock, and cream; bring to a boil. Reduce to a simmer and cook until all vegetables are tender.
Add sage, cloves, nutmeg, cinnamon, and salt and pepper to taste.
Remove bay leaf, and puree.