A great 2-ingredient cocktail with an ugly name, the Rusty Nail was originally made with a not-very-good blended Scotch and Drambuie in equal parts, which made for an overly sweet cocktail. This version is sophisticated and something much more enjoyable, made with a single-malt.
Chill a mixing glass, and add a large ice cube to an Old Fashioned glass or rocks glass for serving. Add Drambuie into the mixing glass. Add the Scotch. Add several ice cubes, and stir for 20 seconds. (Do not shake; stirring will maintain the clarity as it chills the liquor.) Strain over the large cube into the chilled rocks glass.