Stir squash, broth, onion, curry powder, garlic powder and salt together in a 5-quart slow cooker.
Cover and cook until the vegetables are very tender, 7 hours on Low or 3 ½ hours on High.
Turn off heat and stir in coconut milk and lime juice to taste.
Puree with an immersion blender until smooth.
Garnish with cilantro.
