Lyonnese Pumpkin Soup

1,5 kg pumpkin, 1 shallot, 1 leek, 50 g butter, 50 g sugar, 50 cl milk, 50 cl chicken soup, 2 mashed potatoes, 4 spoons Creme fraiche, salt, pepper

Peel the pumpkin, cut it into chunks. Peel the other vegetables and cut them also into cubes. Saute the onion and the leek in melted butter, add the pumpkin, season with salt, pepper and sugar, let it simmer for 10 minutes. Mix the milk with the soup and pour over the pumpkin, add the potatoes, cover and let it simmer for an hour. Mix the soup, add the Creme fraiche, season if necessary and serve hot with croutons.