Pour the wine into a large saucepan and reduce over medium-high heat until it is like syrup and only one half of a cup or so remains. Whisk in cream and butter and continue to whisk until butter has melted.
Meanwhile cut the potatoes into quarters and steam in a stove top steamer until they are tender when pierced with a fork. Drain and place hot potatoes back into the pot.
Pour the wine mixture over steamed potatoes and mash well. Season with salt and pepper and add extra butter, cream or milk if the potatoes seem dry.