“My life blew up. After that I kind of started falling in love, and then I wrote a whole record about that,” she tells Corden. Then, with a broad, luminous smile, she revealed her No. 1 beauty secret: “I’m writing music that’s about happiness and truth.”

Stefani is undertaking a 27-city US tour supporting her latest release, This Is What the Truth Feels Like, a deeply personal album that debuted at No. 1 and includes hit singles Used to Love You, Make Me Like You and Misery.

It’s been a year since Stefani filed for divorce from her husband of 13 years, Bush vocalist Gavin Rossdale, after months of tabloid conjecture about a Rossdale affair with the couple’s nanny.

Speaking from her home in Los Angeles, Stefani says she is “really grateful” for the response to her new music but that writing hit singles that might connect with a young audience, who were toddlers when her Southern California ska-rock band No Doubt broke out two decades ago, was never part of the plan. Stefani began writing to escape what she calls “my darkest hour”.

“Just trying to save my life and get through something I never thought I’d have to get through,” she says. “I remember sitting there being so embarrassed about my life and thinking, ‘God, I’ve got to turn this into something beautiful. I have to make art out of this somehow.’”

Stefani’s first high-profile break-up with long-time boyfriend and No Doubt bandmate Tony Kanal yielded the career-changing 1995 album Tragic Kingdom and the singles Don’t Speak and Just a Girl. The songs and accompanying videos made Stefani – part Barbie, part badass – a style-setting star (who would go on to create the clothing lines L.A.M.B., Harajuku Lovers and Design With Purpose).

Twenty years after Tragic Kingdom, Stefani says the break-up with Rossdale came at a time when she was filled with plenty of doubt. Years of juggling responsibilities to her young sons and requests by her No Doubt bandmates to tour had left her feeling guilty, distracted and creatively insecure. The unravelling of her marriage provided a “wake-up call”, and she forced herself into the studio.

“Sometimes, really bad [things] happen just so that really great things will happen,” she says. “It was really hard, because I just wanted to get under the covers and eat pizza and cry.”

After not being able to write for years, Stefani says the new songs came in a “magical” rush: she wrote Make Me Like You and Misery on consecutive days. While the album includes a few tears, notably on the heavy ballad Used to Love You, the totality of Truth is a portrait of a woman confident, rejuvenated and happily moving on, as Stefani appears to be doing with her new beau, country singer Blake Shelton, her co-star on The Voice.

Misery, with its beautifully rendered, fashion-forward video by long-time collaborator Sophie Muller, is a buoyant appreciation of the giddy euphoria of new love. The video for the club-friendly love song Make Me Like You includes a sly wink to her supermarket fame as she briefly holds up a tabloid magazine with the headline “Gwen Pregnant With Alien Baby.”

The singer, backed by a new band and eight dancers, says her summer concerts will include fan favourites from throughout her solo and No Doubt years, and with hip-hop star Eve as the opening act, the set should include Rich Girl and Let Me Blow Ya Mind.

The shows were designed by Stefani and Muller, a filmmaker who has created iconic videos for Annie Lennox, Björk, Sade, Rihanna and Shakira, so expect lots of costume changes and visual pop.

But Stefani says razzle-dazzle is secondary to her primary goal of creating the kind of personal connection with the audience that she recalls from her first concert, an Emmylou Harris club date she attended in Los Angeles with her parents when she was 7 or 8 years old.

“A weird part about it was, she was halfway through the set and said, ‘OK, I’m going to take a break, because I need to go nurse my new baby.’ And so she went offstage and, for a little girl, that was, ‘What? She’s going to go nurse her baby?’ And then, she came back out,” Stefani says. “I knew all her music growing up … I will never forget that moment.”

Earlier this year, in a festival appearance tied to the release of Truth, Stefani says something didn’t feel right, and she stopped the show and started talking to the audience.

“I was like, ‘Right now, you are going to get to know me. Whatever you think about me – like, everything you read, whatever you think, whatever – this is me right here, and I’m going to make sure that when you walk away, that you know who I am and I’m going to make sure I know you,’” she recalls saying. “That’s what I learned through the years, and that’s what’s important, is really just connecting with the audience in a way that you can only do through music.”