Preheat the grill to its highest setting.
Heat the oil in a saucepan over a medium heat. Add the onions and butter to the saucepan and fry for 4-5 minutes to soften.Add a pinch of nutmeg and cook for a further two minutes.
Add the wine, cream and water to the saucepan and whisk to mix well. Heat to a simmer and cook for a further ten minutes, then add the chives.
Meanwhile, for the croûtons, place the cheese on top of the toast and place under the gril, to cook for 1-2 minutes or,l until bubbling.
To serve, pour the soup into a serving bowl and top with the croûtons.
