Start by cleaning the leeks thoroughly to remove any dirt. Slice them into rounds. Peel your potatoes and cut them into small, even cubes. Finely dice the onion so it cooks evenly.

Melt the butter in a large pot over medium-low heat. Add the leeks and onions to the melted butter. Stir them well to coat them. Cover and cook for 10 minutes until soft.

Stir in the potato cubes and cook for 2 more minutes. Pour in the stock and add the bay leaf and nutmeg. Bring the mixture to a gentle boil, then lower the heat.

Cover the pot with a lid and let it simmer gently. Cook for about 15 to 20 minutes. The soup is ready when the potatoes are very soft and tender when poked.

Remove the bay leaf from the pot and discard it. Use a stick blender to liquidize the soup until it is completely smooth. You can leave some chunks if you prefer.

Pour the milk into the blended soup and stir well. Heat the soup gently on the stove but do not let it boil. This keeps the milk from curdling and keeps it creamy.

Taste the soup and add salt and pepper as needed. Add more nutmeg if you like a warmer flavor. Pour into warm bowls and garnish with fresh chives before serving.