Ethan Slater Did Triple Duty for His Wicked Audition Tape, Playing Boq — as Well as Glinda and Nessarose (Exclusive)

Ethan Slater can do it all!

The actor, 32, auditioned for his role as Boq in Wicked by performing as the character in his audition tape, as well as Glinda (Ariana Grande) and Nessarose (Marissa Bode).

“I did two scenes and sang Boq’s songs, 'The Ozdust Ballroom' and 'March of the Witch Hunters,' which is the second movie," Slater says in PEOPLE's new special Wicked edition.

"But," he continues, "I should say that I didn’t have anyone to read with at the time, so the tape I sent in is me playing Glinda and Nessa off camera, and then me reading with a video of myself."

Calling the decision to play three characters at once in his audition tape "so bold," Slater adds, "I can’t believe I got away with it. But I knew I wanted to take my time with it ...  and I couldn’t get somebody to spend that time with me, so I just did it with myself.”

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Wicked marks Slater's first major film. He had auditioned long ago for Boq on Broadway, though he didn’t get the role.

However, he did later get the title role in Spongebob Squarepants, a musical version of the hit Nickelodeon television series, which earned him a Tony Award nomination.

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The upcoming film adaptation of the Tony-winning Broadway musical, stars Grande, 31, as Glinda, opposite Cynthia Erivo, who portrays Elphaba. (The musical’s original Broadway cast included Kristin Chenoweth and Idina Menzel in the roles, respectively.)

Others who are featured in the project, directed by Jon M. Chu, include Jonathan Bailey as Prince Fiyero Tigelaar, Jeff Goldblum as the Wizard, Michelle Yeoh as Madame Morrible, Peter Dinklage as Dr. Dillamond, Bowen Yang as Pfannee and Bronwyn James as ShenShen.

According to Slater, getting to work with such a large ensemble of talented actors was an experience life no other.

“The thing that felt really special is how much everyone cared about their characters," he tells PEOPLE. "When you’re working on something that’s been around the world for 20 years and these are characters that the fans love and care about, it’s really important that the actors portraying them in a movie of this scale care as much as everyone else. And everyone did."

"To watch Cynthia navigate her love for Elphaba, to watch Ariana navigate her love for Glinda and how they were able to imbue their performances, it was revelatory, it was so beautiful," he continues.

Speaking specifically of Grande, who he is currently dating, Slater says, "One of the things that was really fun to see is, she has a masterful grip on comedy, and she’s so funny and so physical, and it never feels like a joke on top of the character. It always feels like it’s coming right from Glinda. You get lost in the performance — she just is Glinda. Even in those incredibly funny physical moments.”

Buy PEOPLE's Wicked special edition here. Wicked will be released in two parts, with the first arriving in theaters on Friday, Nov. 22.