Heat butter in a skillet over medium heat; cook and stir leeks just until softened, about 8 minutes. Pour water and wine into skillet; bring to a boil. Reduce heat to medium-low, cover, and simmer until leeks are very soft, about 20 minutes.
Remove cover, increase heat to high, and cook leek mixture, stirring constantly, until liquid evaporates, about 8 minutes. Reduce heat to low; stir cream into leek mixture. Cook leeks, stirring, until mixture begins to thicken; stir in Parmesan cheese. Season with salt and pepper.