It’s called an “Old Fashioned” because it’s the literal definition of what a cocktail used to be: a healthy pour of spirit, a bit of syrup, and couple dashes of bitters. No mushed-up fruit, no soda: just Platonic perfection in a glass.
The classic Old Fashioned recipe calls for bourbon, rye or blended whiskey, simple syrup, and aromatic bitters. That said, it’s an endlessly flexible template – mix and match brown spirits, syrup, and bitters to your heart’s delight.