Howie Mandel thinks Simon Cowell is ''irreplaceable''.

The music mogul is currently absent from 'America's Got Talent' after injuring his back earlier this month, and although Howie admits Simon can't be replaced on the show, he's loved spending time alongside Heidi Klum and Sofia Vergara on the panel.

Howie joked: ''To be honest, we realise Simon is irreplaceable, but who doesn't want to partake of the most gorgeous man sandwich in history?

''All kidding aside, Simon, I know he watches the show, we love you, our hearts are with you, buddy. Come back really fast.''

Simon broke his back when he fell off his electric motorcycle earlier this month.

But Howie is hopeful he'll soon be able to return to 'America's Got Talent'.

He told 'Entertainment Tonight': ''That man is like a superhero, you know? His back has been broken in four separate places, he's had a six-hour surgery where they put a rod in his back. I know that he's up and walking and he's working miracles.

''But first and foremost, he's gotta get healthy.''

Howie updated fans on Simon's condition shortly after the accident, saying he was ''doing spectacularly well''.

Speaking about Simon's absence from the show, he shared: ''We didn't know what to expect. I knew that we could expect something spectacular because we have, I believe, the most talented crew in the world, in every possible department.

''We were a little bit in disarray because we were worried. We were worried about our friend, and our boss, and our leader, Simon Cowell, who we hear is doing spectacularly well, considering.

''The latest I've heard is that after a six-hour operation, and some fused discs, and the rod put in his back, yesterday, he was up on his feet, already, he's already mobile!

''So, as I've been saying to a few other people, I wouldn't count out seeing Simon again before this season's end.''