2 ounces blended Scotch whisky (Black Grouse is a nice mid-point)
1 ounce sweet vermouth
2 dashes Angostura bitters
Garnish: lemon or orange twist

Stirred over ice, strained into a chilled cocktail glass, garnished with a maraschino cherry or lemon twist, and served straight up in a chilled glass

See also: http://www.seriouseats.com/recipes/2010/02/rob-roy-scotch-whisky...