Preheat oven to 450 degrees Fahrenheit.
Place the squash on a roasting pan and coat with two tablespoons of oil. Sprinkle the cumin, coriander, and curry powders on top.
Bake the squash for 20 minutes, or until the squash is soft.
While baking, heat a high-rimmed sauce pan over medium with the remaining two tablespoons of oil. Add in the jalapeño, onions, carrots, celery, and garlic and cook the mix until the vegetables are soft, approximately 10 minutes.
Add the squash and the vegetable stock to the pan and bring the mix to a quick boil, then simmer for 5 minutes.
Pour the mix into a blender or food processor, add the lemon juice, and pulse blend to your desired consistency. Add salt and pepper to taste. Top with cream (optional) and serve.