I'd do something like Gardiner + Kapanen + ??, I wouldn't move Marner/Nylander/Matthews though.
While some people may think it would HAVE to include one of those three, I'm really not convinced. Big trades for players like Pronger, Shattenkirk, Kovalchuk, Hossa, B. Richards, Kessel (at least when we traded him away), etc didn't require a piece of that calibre. Star players that aren't under control long-term get traded for packages of ~3 or so pieces, rather than for complete stud young players with pedigree that are also proven at the NHL level.