Carrie Underwood, 42, went back to her “American Idol” roots for the season’s “iconic Idol moments” special on Monday night. For the occasion, the singer — who is now a judge for the singing competition show — chose the exact same dress she wore in 2005 when she won Season 4.

Carrie Underwood chats with ET backstage at 'American Idol' after the show celebrated its own iconic moments, with contestants performing songs made famous by the show and its biggest stars. Carrie reflects on reuniting with some of her fellow season 5 singers and reacts to fellow winner Fantasia's advice for season 23's hopefuls.