Add chopped root vegetables to the slow cooker, along with minced garlic and a sprinkle of cinnamon.
Pour in the vegetable broth and drizzle with olive oil, then season with salt and pepper.
Cover the slow cooker and cook on low for about 6 hours, until the vegetables are very tender and fragrant.
Carefully transfer the cooked vegetables and broth to a blender or use an immersion blender in the pot; blend until smooth and velvety.
Pour the blended soup back into the slow cooker or a pot, taste and adjust seasoning with more salt and pepper if needed.
Gently reheat if necessary, until steaming and warmed through, then ladle into bowls and serve hot.