How to Make It
In a large pot, melt the butter over medium heat. Once the butter is just beginning to brown, add the onion and sauté for 5 minutes. Add the garlic, sugar, cinnamon, pepper, nutmeg and cayenne pepper and cook for 3 minutes. Add the pumpkin puree and broth, stir to incorporate, season with salt and bring to a boil. Reduce the heat to low and simmer for 20 minutes. Stir in the cream and let cool for 10 minutes.
Transfer the soup to a blender (or use an immersion blender in the pot) and puree until smooth. If needed, add additional water or broth to reach desired consistency. Return the mixture to the pot or large a sauce pan. Serve warm and drizzle with crème fraîche.