Some cocktails are born from intricate planning and laborious tinkering, the brainchildren of mad scientist mixologists. Other libations, like the Negroni Sbagliato, happen by happy accident. The Sbagliato is the slightly askew cousin of the Negroni proper, an herbaceous Italian standard that’s equal parts gin, sweet vermouth, and Campari, topped with an orange peel. As the owner of Bar Basso in Milan, Mirko Stocchetto used to whip up the aromatic aperitivo — a pre-meal, appetite-stimulating drink, per Italian custom — dozens of times a day for his thirsty pals in the late 1960s, mindlessly mixing the classic while listening to working-class regulars regale each other with tales of their early-shift shenanigans and weekend travels.

To hear Mirko’s son Maurizio tell it, back then the tapster assumed his position behind bar as if he were a pianist or typist, blindly grabbing bottles from their regular positions “just like the keys on a piano or computer” to serve up his go-to spirits. But one night, when Mirko went to fetch his trusty gin to continue crafting a Negroni for a customer, he pulled a bottle of prosecco that was mistakenly left in its place and poured it in the glass with the other ingredients.