Cut pumpkin in half and scrape out seeds, brush with olive oil and place onto a greased baking tray, cut side down. Bake in preheated oven for about 1 hour until pumpkin is easily pierced with a fork. Allow to cool slightly, scrape out pumpkin flesh
Heat 2 tablespoons olive oil in a large pot and saute leek and garlic for about 5 minutes over medium heat.
Place thyme, bay leaf and parsley in a small cheese cloth, tie closed and put on top of the leeks. (You can also put the herbs loose in the soup, but make sure to remove them before pureeing). Pour in wine and cook for about 5 minutes until most of the wine has evaporated.
Add chicken stock and pumpkin and simmer for 10 minutes. Remove herb bag and puree soup. Season with salt, pepper, creme fraiche and sugar. Finish with a dash of white wine vinegar and serve hot.