Maple syrup might make you think of fall. Or pancakes. But sugaring season—that's when maple trees are tapped for their sap—begins right around now. And despite its breakfast-y nature, this amber-colored goodness has been used to sweeten cocktails since the olden days. Like simple syrup (sugar dissolved in water), maple balances out the sour elements of a drink that contains citrus. Unlike simple syrup, it also delivers a caramel-like depth and flavor.

It blends well with brown...