Liz Gillies Explains How She and BFF Ariana Grande Remain So Close: 'We Make a Real Effort' (Exclusive)

• Elizabeth "Liz" Gillies is opening up about her lasting friendship with Ariana Grande and how they've remained so close since costarring in 13: The Musical and Victorious
• The actress and singer tells PEOPLE audiences will be "gobsmacked" by Grande's performance in Wicked
• Gillies also shares her thoughts on former onscreen Victorious boyfriend Avan Jogia's engagement to pop star Halsey: "I think they might be the hottest couple to ever exist"
  

Friendship is synonymous with Elizabeth "Liz" Gillies and Ariana Grande.

The talented pair met as young teenagers, made their Broadway debuts alongside one another in 13: The Musical and costarred on Nickelodeon's Victorious. They've remained best friends ever since and continuously supported each other's projects, so it should come as no surprise Gillies "couldn't be prouder" of Grande's starring role as Galinda/Glinda in the upcoming Wicked film.

"I know how much this project means to her. When I met her at 13 or 14 years old, Wicked was her show, and Glinda was her girl," the 31-year-old actress and singer tells PEOPLE. "We would sing the songs together, and she would tell me about her dream of playing this role. I know, throughout the audition process, how hard she worked and how much she wanted it. It is so incredibly well-earned."

When Wicked (also starring Cynthia Erivo as Elphaba) hits theaters Nov. 22, Gillies predicts viewers will be "gobsmacked" by Grande's performance. "She is just extraordinary, and I'm so proud of her," she says. "There's truly, at this point, absolutely nothing she cannot do. She's proven that."

Over the past decade-plus since Victorious ended in 2013, the two stars have maintained an incredibly tight-knit bond, displayed in part through their annual Halloween costume recreations of characters from films like Showgirls and Best in Show.

Gillies also appeared in Grande's 2018 "Thank U, Next" music video, popped up at one of her Sweetener Tour shows the following year for a nostalgic rendition of the duet "Give It Up" from their Nickelodeon sitcom and recently supported the Grammy winner as she hosted Saturday Night Live.

The secret to their lasting friendship? "We make a real effort to see each other," explains Gillies. "We laugh, we reminisce and we make new memories. I think a lot of the time when you have friends from childhood, you need to make new memories to keep a friendship going. Otherwise, you're just reminiscing about the past and getting together once a year."

"I see Ariana all the time, and we're constantly doing things, having new experiences and adding chapters to our book," she continues. "I'm so grateful that we've been able to share in this wild ride together, and I can't wait to see what's next. This is a very exciting chapter for her, and I feel very blessed to get to watch it so closely with her."

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Grande isn't the only Victorious alum Gillies remains close with today. In fact, she says some of the main cast members still have an active group chat — mainly for memes or trying to make plans, which is "harder" these days than when most of them spent the bulk of their time in Los Angeles.

"The love is still there, and I hope we get to do something soon together because we have so much fun, and that was such a special time," she says of the series, which costarred Victoria Justice, Matt Bennett, Leon Thomas III and Daniella Monet. "I mean, no one could really understand that time. We're bonded for life over it. It was really special."

One topic of discussion for the next Victorious hangout is Gillies' former onscreen boyfriend Avan Jogia's engagement to pop star Halsey. "I think they might be the hottest couple to ever exist," declares Gillies, who played Jade West on the show opposite Jogia as Beck Oliver.

While the Dynasty star hasn't met Halsey in person yet, she says, "I'm sure she's absolutely wonderful because he's just such an incredible guy. He really only surrounds himself with good, good people, and he seems so happy."

"I mean, if it couldn't be Beck and Jade, this might even be better," she adds. "They are awesome together."

Gillies is set to perform a limited run of shows at Café Carlyle in New York City from Nov. 6 to Nov. 9, and she recently released a new single, "What You've Done," with Ferry Townes.