Malt is a common milkshake additive that is used to enhance the flavor and texture of the drink. It is made from barley, which is a cereal grain that has been sprouted and then dried. Malt is often used in baking and brewing, and it can also be added to milkshakes to give them a richer flavor. Malt is a popular choice for milkshake additives because it adds sweetness and a creamy texture to the drink.