Nobody knows exactly who invented the first recipe for an Amaretto Sour. It was somewhere in the US, and sometime in the 1970s, that Italian liquors became more popular in America. Back then it was common in bars to have a sour mixture available. When a customer asked for a whiskey sour that was fashionable at the time, the bartender simply used the whiskey and blend. Somewhere a bartender was clearly wondering what it would taste like if you also added amaretto or replaced whiskey with amaretto…, and so the cocktail was born.