For a richer flavor, roast the kabocha squash with olive oil and a pinch of salt before adding it to the soup. If you don't have an immersion blender, you can purée the soup in batches using a regular blender. Be cautious when blending hot liquids. Garnish with fresh herbs, a drizzle of chile-infused olive oil, and balsamic fig vinegar or a balsamic reduction for an elegant presentation.