Courtney Hadwin, 14, showed off her explosive musical ... She walked onstage shyly before revealing her massive voice — and earning the golden buzzer from Mandel. “You are not from this ...

"It was the best experience of my life," Courtney Hadwin told PEOPLE ... During her run, Hadwin, who previously made the top 10 on The Voice U.K., belted out Tina Turner’s 1988 classic ...