Spray 4- to 5- quart slow cooker with cooking spray. In cooker, toss squash, apple, onion, curry powder, salt and white pepper. Pour broth over vegetable mixture.
Cover; cook on Low heat setting 8 to 10 hours.
Pour about 3 cups of the soup mixture into blender; add coconut milk and brown sugar. Cover and blend until smooth; return to cooker. Blend remaining soup mixture, in 2 more batches of 3 cups each, until smooth; return to cooker.
Increase heat setting to High. Cover; cook 10 to 15 minutes longer or unto hot. Serve topped with chopped apple.