1. Add the chicken stock, potatoes and leeks to a medium pot and bring to a boil.
2. Season with salt and simmer covered for about 20-30 minutes, or until the vegetables are tender.
3. Remove from the heat and use a KitchenAid Immersion Blender to puree the soup.
4. Chill the soup for 1-2 hours. After chilling, whisk in 1/2 cup heavy cream.
5. Garnish with a sprinkle of chives and serve.