By Peter Marks, The Washington Post Ben Platt, who more than three years ago spoke the words and sang the music of “Dear Evan Hansen” for the first time, going on to win the Tony Award in June for best actor in a musical, will leave the celebrated musical in the fall, the show’s producers announced Monday. His last performance at Broadway’s Music Box Theatre, where the show collected a total of six Tonys, will be on Sunday, Nov.