In a hot cast iron dutch oven or pot, melt butter until it turns brown on medium high heat. Add onion, apple and garlic and cook for about 5 minutes. Add the squash and cook for 10 minutes. Pour in hot broth and bring to a boil and cover. Reduce heat to a simmer for 20 minutes on low heat until squash is very soft. Add cream, blend with an immersion blender. Adjust seasoning once the soup is blended and strained.