Penicillin

The Origin

Sam Ross developed the Penicillin at Milk & Honey on Eldridge Street in New York in 2005, working in the environment that Sasha Petraske had created and that defined the standards of the contemporary cocktail revival more completely than any other single venue. The name was a piece of wordplay on the antibiotic, connecting the drink's restorative character, the warming heat of ginger, the sweetness of honey, the brightness of lemon, and the medicinal smokiness of Islay Scotch, to the pharmaceutical that had changed the treatment of infection. Whether the drink is genuinely restorative in the medical sense is debatable. That it has become one of the most ordered modern classics in serious cocktail bars worldwide is not.

Ross's decision to create the Penicillin around Scotch whisky was not an obvious one in the context of the revival's primary reference points, which were predominantly gin-based classics and American whiskey drinks. Scotch had a significant presence in the stirred, spirit-forward tradition of the Rob Roy and the Blood & Sand, but its application to a shaken sour with honey, ginger, and a peated float was genuinely original. The drink's success established Scotch as a sour base in the contemporary bar repertoire in a way that it had not been before, and the Penicillin is largely responsible for the subsequent generation of Scotch-based sours that followed it.

The Honey-Ginger Syrup

The honey-ginger syrup is the technical contribution that most defines the Penicillin's character and the element that requires the most preparation of any ingredient in the build. Making it correctly is not complicated but it requires advance planning that a simple syrup does not. The honey provides floral sweetness and the botanical complexity discussed in the Bee's Knees and Honey Sour entries. The fresh ginger provides a sharp, spiced heat that is specifically different from the dried ginger character found in most commercially produced ginger syrups or ginger beers.

The ratio of honey to water, two to one, produces a syrup with enough body and sweetness to balance the lemon juice and provide the mid-palate weight the Scotch base requires. The ginger steeping time determines the heat level of the finished syrup, which directly determines the heat level of the finished drink. A 30-minute steep produces a syrup with a clean, present ginger heat that is clearly identifiable but not dominant. A two-hour steep produces something considerably more assertive. Both are correct for different preferences. The steeping time is worth standardising once you have found the level that works for the balance you prefer, and the syrup should be produced consistently thereafter.

The Float Technique

The Islay single malt float is the technique that most clearly separates the Penicillin from a standard Scotch sour and the element most commonly mishandled in versions that do not achieve the drink's intended character. The float works by exploiting the difference in density between the finished sour, which has been diluted and chilled during the shake, and the undiluted Islay malt, which is poured over the back of a bar spoon held just above the surface of the drink. The spoon disperses the malt as it lands, preventing it from punching through the sour below and allowing it to sit as a distinct aromatic layer on the surface.

The purpose is experiential rather than structural. The Islay malt's smoke and maritime aromatics, its peat, iodine, and saline character, are encountered at the nose before the drink reaches the lips and on the first sip before the honey-ginger and lemon of the body take over. That sequence of smoke at the approach giving way to sweetness and acid in the drink is the Penicillin's defining characteristic and the experience that makes it memorable rather than simply well-balanced. A float poured incorrectly, too fast or from too high, breaks through the surface and partially incorporates into the sour below. The drink remains good but the progression that defines it is lost.

Islay Malt Selection

The choice of Islay single malt for the float is one of the more consequential decisions in building the Penicillin because the float must be assertive enough to be present at the nose and on the first sip despite its modest 7.5ml volume. Lightly peated or non-peated single malts will not provide the aromatic presence the float requires and produce a drink in which the smoke element is barely perceptible. The Islay style, with its characteristically high phenol content and its maritime, iodine-inflected peat character, is the correct choice because it is the only Scotch style assertive enough to register at 7.5ml as a surface element.

Laphroaig 10 Year is the most commonly cited choice and performs consistently well. Its medicinal, intensely peated character sits against the honey-ginger sour in a way that is immediately arresting without being unpleasant for those who approach it without prior experience of heavily peated Scotch. Ardbeg 10 Year is the alternative most commonly used by bartenders who want a slightly drier, more saline result. Both are correct. The choice between them is a matter of the specific smoke and maritime character preferred.

The Blended Scotch Foundation

The blended Scotch base is as important to the Penicillin as the Islay float and is more commonly treated as an afterthought. A quality blend with genuine malt character, Monkey Shoulder, Famous Grouse, or Chivas Regal 12 Year, provides a foundation with enough complexity to interact with the honey-ginger syrup and lemon juice as a three-way balance rather than simply providing the alcohol. A thin or neutral blend disappears behind the honey and ginger and produces a drink that tastes of the syrup and lemon with a Scotch note rather than a Scotch sour with a honey-ginger modification.

The blended base and the Islay float work as a complementary pair rather than as competing elements. The blend provides grain sweetness, gentle malt, and modest smoke. The float provides intense smoke, peat, and maritime character. Together they produce a complete Scotch experience across the aromatic range of the spirit that a single expression at the same total volume could not achieve.

How to Serve It

Shaken and strained over a single large ice cube in a rocks glass, with the Islay float applied carefully over the back of a bar spoon and candied ginger on the rim. Serve it immediately and give the drinker enough time with it to experience the progression from first sip to last as the float integrates gradually into the sour below. The Penicillin is not a drink that is the same from beginning to end, and that development across the glass is as much a part of what it is as the balance of its ingredients. Build it properly and give it the attention it asks for.