Pour over ice in a mixing glass //
Serve in a small wineglass //
garnish with nutmeg (optional)
This is a serious but surprisingly drinkable cocktail that responds well to variation. Grand Marnier works well with ruby port, but Cointreau or just triple sec and tawny port also make a great combination.
You can also serve neat, which has become known as 'the winter drink' among our circle.
This recipie: 1999 Williams-Sonoma Bar Guide
An Alternative: http://www.imbibemagazine.com/Recipes/Brandy-Sangaree-Recipe