When customers recognize your product’s taste as your brand, you have something you can carry into new formats and occasions. For most of my life, Reese’s was peanut butter cups and the Pieces Elliott shared with E.T. “Two great tastes that taste great together,” as the old ads put it after chocolate collided with peanut butter in the happiest of accidents. Over time, that combination became a single taste we recognize as Reese’s. (Although the chocolate seems to be eroding into...