Really just a Scotch on the rocks with a bit of Drambuie, I’ve found it even more satisfying when made along the lines of an Old Fashioned. The natural combination of Scotch and Drambuie had been around since Prohibition, operating under a couple different names, until it received official christening as a “Rusty Nail” at some point in the ’50s. I’ve seen ratios as high as half-Scotch and half-Drambuie – way too sweet. Dry it out some and round it up with lemon oil and Angostura; you’ll want to take your time sipping it that way.
Muddle lemon zest, Drambuie and bitters well and mix to express lemon oil, but don’t shred the lemon zest.
Add a large ice chunk or two to three ice cubes then add the Scotch.
Stir briskly to blend and chill.