In a large pot, sauté the chopped onion and garlic until they become fragrant and translucent.
Add the pumpkin puree and vegetable broth. Stir well and let it simmer for about 20 minutes.
Use an immersion blender to puree the soup until smooth. If you don't have an immersion blender, carefully transfer the soup in batches to a regular blender.
Return the blended soup to the pot, and stir in the heavy cream and ground nutmeg.
Season with salt and pepper to taste. Adjust the seasonings as needed.
Simmer for an additional 1 minute to heat through.
Serve the Pumpkin Soup hot with a dollop of sour cream and a sprinkle of fresh herbs.