Preheat oven to 400 Deg F. Peel, cut in half, and de-seed butternut squash. Cut into strips then into 1-2 inch chunks. Place in a bowl. Drizzle one tablespoon over the squash then spread out on a baking sheet. Season with nutmeg and cloves.
Roast the squash for 25 minutes or until fork tender
While the squash is roasting heat a large stock pot or Dutch oven, add remaining oil, the butter and sauté onions, celery, carrot, and garlic until soft, about 5-7minutes. Season with the salt and pepper.
Add chicken stock to the sautéed vegetables and stir
Add in butternut squash to stock mixture once it is removed from oven
Bring to a boil then let simmer for 30 minutes, stirring occasionally
Transfer in batches to a blender and puree until very smooth. You can also use an immersion blender. If you don't have high powered blender, strain the soup with a mesh strainer back into the dutch oven
Add brown sugar, cream and fish sauce, stir well then bring to a simmer. Taste and season with more salt and pepper if desired
Serve with a sprinkle of grated nutmeg and a few dashes of your favorite hot sauce