Add the cubed butternut squash, diced onion, minced garlic, and grated ginger to the slow cooker.
Pour in the vegetable broth, then stir in the cumin, turmeric, salt, and black pepper.
Cover and cook on low for 7 hours until the squash is very soft.
Use an immersion blender to puree the soup directly in the slow cooker until smooth.
Stir in the coconut milk and let the soup warm for 10 more minutes on low.
Ladle into bowls and top with fresh cilantro. Serve with lime wedges on the side.