Kristin Chenoweth previews A Very Wicked Halloween and reflects on 15 years of Wicked

Wicked is marking its 15th anniversary this year, and NBC is celebrating the Glinda (and Elphaba) way! The network reunited the show's original stars, Kristin Chenoweth and Idina Menzel, for A Very Wicked Halloween, a special night of performances and more. Chenoweth tells EW the evening made her ugly-cry. "I didn’t realize it was going to be so emotional," she says. "It’s been a fun journey, and I can’t believe it’s been 15 years." Click through for a sneak peek at the special and more memories from Chenoweth.

Chenoweth and Menzel will be singing throughout the broadcast and hosting the proceedings. "Even if we were just appearing [and not hosting], it would still feel that way because we were there from the beginning," says Chenoweth. “We were the original ones, and we had experiences nobody can know because we did it. We were both looking at each other going, ‘This is so cool.’”

The evening is packed with performances, from the likes of Pentatonix, Ariana Grande, Adam Lambert and Ledisi, and more. Chenoweth calls the affair "one of the best concerts I've ever seen," adding, "Pentatonix killed it. Adam Lambert and Ledisi [are] unbelievable. Of course, my baby Ariana was incredible."

Pop star Ariana Grande, a longtime Wicked superfan, previously revealed that she'll be singing "The Wizard and I" on the special. Chenoweth tells EW that Grande loved another song which is no longer in the show, having been replaced by "The Wizard and I."

“It was called ‘Making Good,’” Chenoweth says. "It was about how you make something good and you make it great. Those lyrics stuck with me all these years. I wish Idina could release it or somebody could do it. It’d be cool. I loved it."

The anniversary special brought many memories rushing back to Chenoweth, including the first time she donned Glinda's iconic bubble dress, crown, and wand. "You feel like a fairy princess. You can’t believe it’s happening," she says. "It weighed a lot. The crown was really heavy, and the wand was really heavy. They’ve gotten over time where they’re much lighter, but I just remember it being heavy, but thinking it’s so worth it."

For Chenoweth, "For Good," one of the show's most enduring duets, is a personal favorite and the song that made the most lasting impression. "The first time Idina and I were learning 'For Good' together with [composer and lyricist] Stephen Schwartz, I knew," she says. "He brought it in and I was like, 'Oh, this is the whole point of the show.' That was a pretty big moment." Chenoweth still regularly sings the song in concert, and it's stayed with her like a handprint on her heart. "That lyric, I look at certain women in my life and I think 'Oh, they've left a handprint on my heart,' and each are different and special in their own way."

For Chenoweth, the key to Glinda's character can be found in her most famous song, "Popular." As she explains, “‘Popular’ was an interesting assignment because it's repetitive on purpose. [Glinda] is not going to repeat an outfit, she's not going to repeat a lipstick, and all she wants to do is make her presentation good. Her presentation has to be good, and then she's nailed it.” Over the years, Chenoweth has changed up that number to reflect changing times, including for the broadcast. "Glinda would thrive in social media today," she says. "I changed it up a little bit for this broadcast. I've done it differently over the years, but Glinda in 2018 is alive and well."

The original Wicked novel, by Gregory Maguire, is much darker than the musical (Fiyero and Elphaba die!), and Chenoweth reveals that the script originally hewed more closely to the book. "We did have a darker script," she says. "How much can the audience stand? Especially in musical theater, when we're built to have a song come in because we can't speak anymore. We did have a darker version, but ultimately it changed and changed, and we found the right tone. It's interesting with these two women — who's good and who's evil? Both are, and that's what I love about it."

Chenoweth's time in the show (which started way back when it was in early workshops) was not without stressful moments. She tells EW about a performance when her new puppy, Madeline Kahn Chenoweth, ate rat poison in her dressing room. “It was five minutes before curtain. I had my dress on even, but I said, ‘I'm not going on,’” she remembers. Producer Marc Platt convinced her to go on and took Chenoweth's dog to the vet himself. "She came home the next day and her stomach was pumped and the bracelet around her wrist said 'Maddie Platt, Wicked,' and that was funny," she says. "She was with us the whole time [after that]. [Costar] Joey Grey tried to train her. I'm sure she went into Idina's dressing room unannounced."

Wicked composer and lyricist Stephen Schwartz was on hand to witness A Very Wicked Halloween, including an onstage reunion with Menzel and Chenoweth and all past and current Glindas and Elphabas. “I asked Stephen Schwartz after it was over, ‘What's it feel like for you? Are you so happy?’” recounts Chenoweth. “He said, ‘It's really overwhelming to see people in the audience singing along.’”

Wicked is a show that defied the odds. After opening to middling reviews both in San Francisco and on Broadway, and losing the Best Musical Tony to Avenue Q, the show became a veritable cultural phenomenom that continues to resonate 15 years later. Chenoweth says that trajectory was, if not evident, at least slightly visible in early crowd reactions. During the San Francisco run, she says, “I knew then that we had something that touched people big-time, and that was a good feeling to know because you see the audience reaction, and I'm like, ‘Oh crap, this is cool.’”

A Very Wicked Halloween was a chance for Chenoweth and others to reflect on 15 years of Wicked and what it's meant to their lives. For her, the timing was perfect. "I don't know it if had come earlier in my life if I could have appreciated it as much," she says of the anniversary concert. "When I was experiencing Wicked 15 years ago, I was living my best life. I was having fun, but you just keep thinking about the next thing. Then, before you know it, it's 15 years and you're back and you're doing it again. It's really special. In show business, we don't have things that last more than 15 seconds. We have something that lasted 15 years and way beyond. We should be so lucky as artists to have that attached to us."

A Very Wicked Halloween airs Monday, Oct. 29, at 10 p.m. ET on NBC.