With just three ingredients: scotch, Drambuie, and ice, the Rusty Nail is a great example of how the simplest cocktails can be the most interesting. What makes this cocktail so intriguing is how the flavors change as everything gets to know each other.
The key to a good Rusty Nail is making sure to give it a good long stir with the ice. The addition of ice to the scotch and Drambuie dramatically changes the taste of the drink and brings everything together.
The ratio for this drink changes around a bit, depending on who's writing the recipe, with a higher ratio of scotch to drambuie referred to as making the drink drier. What we like in the 3 to 1 ratio used here is how the honey in the Drambuie layers a soft sweetness over the scotch. For our taste, the Drambuie overpowered the scotch in the 1 to 1 and 2 to 1 ratio mixes we tried.
Some recipes like to add a dash of Angostura bitters, which we don't think is needed. In our testing the bitters added to much complexity, bringing a roundness to the whole affair that muddied the clean simplicity that we like in our Rusty Nails.
With it's mellow flavors the Rusty Nail is a great choice for a nightcap or as a sipping cocktail.
Combine the scotch and Drambuie in an old fashioned glass or cocktail shaker.
Add ice and stir for 45 seconds or so to chill and combine the flavors.
Serve over ice in an old fashioned glass.
If you want to make your own rusty nail stirring stick, start by blunting the end of a clean nail with a hammer. Then sterilize the nail in boiling water or running it through a good dishwater a few times.