Kelly Clarkson once wrote a song between ordering sushi and her food arriving.

The 43-year-old pop star has revealed that she wrote Underneath the Tree - which features on her 2013 Christmas album, Wrapped in Red - while she was waiting for her food to arrive.

Asked which song took her the shortest amount of time to write, she told The Kelly Clarkson Show's YouTube channel: "A Christmas song. It was Underneath the Tree. I was working with Greg Kurstin in the studio.

"I ordered sushi and when it arrived I had written it."

Kelly admitted that she finds it really easy to write Christmas songs, because she's a huge fan of the festive season.

She said: "I think because I really love Christmas I write them really quickly for Christmas -- because they feel good, because you can be a little cheesy, you know? You don't have to worry about being cool, which honestly that's not a concern generally ever because I'm not."

Kelly became the inaugural winner of American Idol back in 2002. However, the pop star recently claimed that she didn't realise American Idol was a TV show prior to auditioning.

The Behind These Hazel Eyes hitmaker said on the Not Gonna Lie podcast: "For all of us in that first season, we literally didn't ... I didn't even know it was a TV show until my third audition.

"Like, we were literally trying to pay our bills. We're like, 'Oh, this might work. I might meet someone or whatever.' Nobody knew it was gonna amount to anything.

"We were literally, like, kids - you know, 19 years old just trying to pay my electric bill y'all. You know, and afford the deductible on my car that was bashed in that I couldn't afford. So it was a different thing."

Kelly's American Idol experience propelled her towards stardom. But the pop singer recalled feeling isolated at the time.

The chart-topping star - who has hosted her own TV chat-show since 2019 - said: "I had no one. I was the first winner. It was hard. Not to sound like, whatever, it was really hard."