'You were this shy little thing when you came out.
"Bloody hell, Courtney", Simon Cowell said. "And then you sing and you're like a lion", Cowell told her. "I mean, genuinely, incredible".
However, it was Howie Mandel who was really impressed by the performance. "Oh my gosh! You are not from this era". "I'm a huge Janis Joplin fan". Clive Davis, he, goes to the Monterey Pop Festival and he sees this young girl that nobody has ever seen before, that nobody knows.
Fellow judge Howie Mandel was also blown away by Courtney, describing her as being like someone from a different era, before he pressed the Golden Buzzer - to signal that she has made through to the live shows in the competition.
She first went viral when a video of her singing at her school lunchtime open mic session got loads of views on YouTube.
"I'm not Clive Davis, I'm Howie Mandel". Courtney danced around on stage, belting out the lyrics, while everyone in the audience was shocked by the young performer.
Each judge gets to press the golden buzzer only once per series for acts they think deserve to go straight to the quarter finals, bypassing the next rounds of auditions.
And the young talent is no stranger to the limelight of TV, having already stared in the ITV's The Voice Kids past year.