Cut the top end off the head of garlic, so that the bulb remains intact and the cloves are exposed. Remove any of the really loose outer layers. Place on a piece of aluminum foil, then drizzle with olive oil and sprinkle with salt and pepper. Wrap up in the foil then bake for about 50 minutes, until tender and the cloves are golden brown. Once cool enough to handle, squeeze the cloves out of the peel, then use a fork to mash into a paste.
Measure out 1 tablespoon of the mashed garlic to use in the soup. Any extra can be stored in a container in the fridge for use in whatever you like (use it in place of regular garlic in other recipes!).
For the soup
Set a large stockpot or dutch oven over medium heat. Add in the olive oil. When hot, add in the onion and cook until it starts to soften, about 2 to 3 minutes. Add in the carrots and butternut squash. Cook for about 8 to 10 minutes, stirring occasionally, until they start to soften. Pour in 2 ½ cups of the stock, then bring the mixture to a boil. Reduce the heat and simmer for about 10 to 15 minutes, or until the squash is tender. Remove from the heat, then stir in the 1 tablespoon roasted garlic, the ginger, salt, pepper and nutmeg.
Carefully transfer the mixture to a blender and process until smooth (It's easier if you do this in batches). Returned the pureed soup to the stockpot. Pour in the fresh milk and fresh cream and mix to combine. Add additional stock to get the soup to your desired consistency. Season with additional salt and pepper to taste.
Serve the soup garnished with a drizzle of additional fresh cream.