1
: In a large saucepan, melt butter over low heat. Add leeks, cover and cook 10 minutes or until very soft (do not brown), stirring occasionally. Add potatoes and stock. Bring to a boil, then reduce to simmer. Cover and cook for 20 minutes or until potatoes are tender. Remove from heat.
2
: Purée soup with an immersion blender or in food processor. Cool slightly, then stir in evaporated milk, salt and pepper. Transfer to a non-metallic dish. Cover and refrigerate until cold, about 6 hours or overnight. Check seasoning. Garnish with chopped parsley or chives.