Place potatoes in large saucepan, add stock and water. Boil potatoes until tender, about 20 - 25 minutes.
In another saucepan, place milk, leek, garlic and bay leaf and bring to the boil and simmer until leek is softened, about 20 minutes.
Drain, reserving the liquid. Discard the bay leaf.
In the same saucepan, place the cabbage and 60 ml of water, cover, and gently boil until cabbage is tender, about 10 - 15 minutes.
Drain, squeeze cabbage and finely chop.
Drain the potato, transferring to a large bowl. Add the milk and garlic and mash well.
Stir in the leek, cabbage, nutmeg, salt, pepper and butter.
Top with chives.