"I think what's so remarkable about his performance is not only that he is funny and mischievous and quite mysterious, as well — just like the Willy Wonka that people will know — but also, he brings such heart to the role and he's a brilliant actor," says King, 44.
"He's incredibly emotionally intelligent and can bring a great deal of emotional truth to the role."
The director says fans of Chalamet might be surprised that he "can also sing and dance brilliantly," on top of his thespian chops.
"It's really a tour de force for him there," King says of Chalamet's performance, adding, "He was rehearsing for months before we went to kind of that honing skills, which was a pleasure to watch."
Asked how much chocolate the cast and crew consumed on set, King tells PEOPLE it was a "great deal, which was a wonderful thing" that reminded him that his "life had taken a wonderful turn."
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