The classic Irish Coffee is one of those cocktails that has so few ingredients, really nailing it is a study in (1) quality and (2) balance. Though blissfully simple to make -- simply stir whiskey, coffee, and sugar together, then top with whipped cream -- the devil is really in the details. Too much whiskey makes for an overly bitter, boozy bite. The whipped cream should be fresh and only very lightly whipped, so it's airy enough to float on top of the drink but still liquid enough to be sipped. Demerara sugar adds a caramel complexity that regular refined sugar lacks. And bad coffee can be the worst offender, since the coffee itself comprises the biggest part of the drink.