Whiskey is made by fermenting grain that has first been treated with malt enzymes to convert the starch into sugar. The fermented mash is then distilled. The types of grain used, the method of distillation, and the aging process determine the type of whiskey. Irish and bourbon whiskeys can each be used to give their characteristic nuances to a sauce. Scotch whisky, with its classic smoky flavor, is rarely appropriate for sauce making. Whiskey can be used as a substitute for Cognac. The result is different but can be very satisfying.