Heat a 3-qt. chef's pan over medium heat. When the rim of the pan is hot to the touch add the olive oil. Allow the oil to heat an additional minute. Add the onions, carrots, celery, garlic and pumpkin. Sauté for 5 minutes.
Add the curry powder, bay leaves and thyme and continue to cook for an additional 5 minutes. Pour the stock into the pan and bring to a boil. Reduce the heat to a simmer and continue to cook until the pumpkin is very soft, about 25 minutes. Remove the bay leaves and thyme.
Puree the soup mixture in a food processor or with an immersion blender until smooth. Season with salt and pepper to taste.
Combine the crème fraiche or sour cream with the chopped cilantro in a small bowl. Mix well.
To serve, ladle the hot soup into bowls and garnish with a dollop of the cream and herb mixture.