I love Irish coffee.
The Kolkata cafes possibly doesn't use whisky (or, as the Irish would say, whiskey) in theirs. I suppose you'd need a bar license or whatever for that.
I don't really care. Irish coffee tastes mighty good, even without the alcohol in it. The cream, whipped or not, crams the surface, never revealing the coffee beneath if you go for a bird's eye view. It's rich, black coffee of the highest order, and though you cannot taste what's lying beneath without touching the surface, it's worth the wait, trust me.
Leonardo da Vinci used to add another layer to his cryptic world: he wrote them on papyrus, and wrapped them around vinegar-filled glass vials before putting them inside the containers. If you smashed the container, the vinegar would dissolve the papyrus.
The Irish do the same. The moment you try to try stir it, force your way through to the coffee. The trick is to add sugar real slow, around the edge, so that the cream doesn't dissolve, and remains at peace, making friends with this new alien entity.
And then, you drink it slowly. The feeling is surreal. Since you've been good to the coffee, it would try its level best to fill your senses.
And once you're through, after a lifetime, or maybe a million years, you'd notice how transparent the container was.
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The alcohol, as I have mentioned earlier, is strictly optional, unless you're too keen to fall down on the staircases and bruise your elbow.