Tucked away about an hour north of Dublin, the Slane Distillery, once a horse stable, is now a cosy bar serving the best Irish Coffee you can find. Usually associated with a random blend of alcohol, cream, and coffee, the Irish Coffee at Slane Distillery is an exciting change, reminiscent of a chilly, rainy day. A delightful blend of a double shot of espresso softened with fine whiskey and mildly sweetened with vanilla-infused Demerara syrup, all topped with airy whipped cream and chocolate shavings carrying a hint of orange. This perfection of coffee to cream and syrup ratio, minimally sweet and grounded by the vanilla and sherry hints in the whiskey, has been etched into my memory.

Irish Coffee, often a staple in St. Patrick's Day celebrations, is more a fusion of Irish-American culture than pure Irish. The popular belief is that it was first concocted in 1952 at the Buena Vista restaurant in San Francisco when a customer attempted to replicate a favourite coffee beverage he savoured at the Shannon airport. The original cocktail combined aged and frothed cream, two sugar cubes, steamy coffee, and Irish whiskey. As the drink gained popularity, it was reinterpreted several ways, often being overly creamed and sweet, sometimes even including Irish cream liqueur or commercial flavour syrups.

In the hands of an expert, an Irish Coffee is more than just a refreshing brew - it becomes a picturesque layered cocktail. Irish Coffee professional and former beverage director of Manhattan's The Dead Rabbit, Jillian Vose, pointed out the importance of a smaller glass for an Irish Coffee. A balance of one ounce whiskey to six ounces coffee is deemed the perfect ratio. She warns, "Using a large glass spells a boozy, bitter coffee and unsweetened beverage. It'll also get cold halfway through."

Another mistake to avoid is using low quality, stale coffee. Vose recommends strong, freshly brewed coffee that you would savour as is, with minimal add-ons. As Alex Conyngham, the co-founder of Slane Distillery, points out, a sparing use of sweeteners lets the drink shine. They use a vanilla-infused syrup to bring out the vanilla nuances inherent to their virgin oak cask.

Quality remains crucial, and the choice of whiskey plays a monumental role. Try reliable brands like Jameson and Bushmills or venture into new realms with Slane and Teeling. Don’t forget the whipped cream on top - ditch the canned variety and go for the real heavy cream, whipped till it's thick but not stiff. As Conyngham explains, the cream should be frothy enough to float on the coffee, giving it the look of a flawlessly poured Guinness!

Crafting the perfect Irish Coffee calls for creativity, care, and a keen sense of taste. A blend of strong coffee, a measure of sweetener, a splash of quality whiskey, all topped with thick-creamed froth – the perfect Irish Coffee indeed!