"One night I was reading that Katy was coming to Melbourne to appear at the Women's World Cup Cricket final last year in March," Benson told news.com.au.
"I am a big fan of American Idol [on which Katy Perry is a judge] … the showrunner on American Idol happens to be my first boss in television.
"As soon as I saw Katy Perry was coming to Melbourne, I sent her [the showrunner] an email and I said, 'we have been using Katy's song (Hot 'n' Cold) as our title track for 12 years. Please, Trish, can you ask Katy if she wouldn't mind coming to MasterChef while she's in Melbourne?'"
Benson didn't have to wait long for a reply.
"I got an email five minutes later saying, 'she's up for it', and that was it!" he told news.com.au.
"I've worked in the industry now for 25 years and I've worked with some big, big names. The only person I've really been starstruck by is Diego Maradona, I worked with him in the UK. But I've got to say, I was excited to get a photo with Katy Perry," Benson added.
Once she was on set, Perry was given free reign to do what she liked. She played with the contestants, made up fun little songs about some of them, and even called Jock Zonfrillo "daddy".
"She was brilliant," Benson told news.com.au. "She broke the fourth wall – she kept looking at the camera – and she kept walking up behind the contestants.
"She literally took the roof off this kitchen," he said.
Reece Hignell reveals what Katy Perry was really like
One of last year's most popular contestants, Reece Hignell, was arguably the most excited when Perry entered the MasterChef kitchen.
"We lost our minds completely," he told news.com.au last year. "It just didn't seem like something that would ever happen."
And what viewers saw on screen was exactly what Perry was like in person, Reece said.
"She walked in and did not leave," he told news.com.au. "The whole time she was there, she was on. She didn't leave the floor once.
"She spent the whole time walking around trolling us, but it was the most endearing thing. She was like, 'Oh, is this cake going to cook in time?' I was like, 'Katy, it's got half an hour to cook,' and she said, 'Hmm, cakes take longer than half an hour.' I was like, 'Leave me alone!'" Reece laughed.
After filming the guest spot, Reece said the singer hung around for a quick chat with the contestants.
"She stuck around briefly afterwards and we did a few publicity photos," he said.
"I had a chat to her for about five minutes. We were just chatting about the competition and she was in disbelief that we have to walk in every day and cook without a recipe.
"She was shocked that we had to come up with all of our ideas on the spot, so that was really cool that she gave us a bit of respect," Reece said.
