You've heard of a fine, aged wine, but how about a vintage Manhattan?

Some bartenders are shaking up tradition by aging classic cocktails in barrels for several weeks to produce drinks with deeper, more nuanced flavours.

Taking cocktails to the next level.

"What the barrels do is soften everything out and integrate the flavours," says Hugh Reynolds, bar manager of Temple Bar in Massachusetts.

When aging cocktails, you don't want to use fresh ingredients, which could spoil. And bartenders mostly have been using liquors that can stand up to the flavours of charred oak, like gin with its botanical aromas. With vermouth, a staple in many cocktails, you get a little oxidation, but that's not necessarily a bad thing, says Reynolds.