Place the cubed butternut squash, rinsed lentils, diced onion, and minced garlic into the slow cooker.
Add the curry powder, cumin, salt, and black pepper, then pour in the vegetable broth and coconut milk.
Stir everything together until the spices are evenly distributed and the coconut milk is well combined with the broth.
Cover and cook on low for 6 to 7 hours or on high for 3 to 4 hours, until the lentils are tender and the squash is soft.
Taste and adjust salt or pepper if needed. Ladle into bowls and top with chopped cilantro. Serve with lime wedges on the side.