Heat oil in a large sauce pot. Sauté onions, carrots, celery, and potatoes until tender. Add stock and allow to boil. Cook soup for 20-30 minutes to marry the flavors.
In small batches, puree soup in a food processor or blender. Please be careful not to fill the processor bowl as hot liquid expands quickly when blending. Place pureed soup back into soup pot to reheat. Add cream, nutmeg and ginger. Salt and pepper to taste.