Photo: Idina Menzel Poses With Ariana Grande at A VERY WICKED HALLOWEEN

Last night, Wicked taped its 15th anniversary special, "A Very Wicked Halloween."

"A Very Wicked Halloween: Celebrating 15 Years on Broadway" reunited Tony Award Winners Idina Menzel and Kristin Chenoweth, the original Elphaba and Glinda, who performed and served as hosts for the special. Additional guest performers include global music superstar Ariana Grande, multi-platinum recording artist Pentatonix, Adam Lambert, Ledisi, the current Broadway company of Wicked and more.

"A Very Wicked Halloween: Celebrating 15 Years on Broadway," will air on NBC Monday, October 29 at 10pm ET/PT.

Last night, Menzel took to Instagram to post a photo with Grande, of whom she says she's a "huge fan." Check it out below!

The Broadway sensation Wicked looks at what happened in the Land of Oz...but from a different angle. Long before Dorothy arrives, there is another young woman, born with emerald-green skin, who is smart, fiery, misunderstood, and possessing an extraordinary talent. When she meets a bubbly blonde who is exceptionally popular, their initial rivalry turns into the unlikeliest of friendships...until the world decides to call one "good," and the other one "wicked."

With a thrilling score that includes the hits "Defying Gravity," "Popular" and "For Good," Wicked has been hailed by The New York Times as "the defining musical of the decade," and by Time Magazine as "a magical Broadway musical with brains, heart, and courage."

Winner of over 100 international awards including the Grammy Award and three Tony Awards, Wicked has been performed in over 100 cities in 14 countries around the world (U.S., Canada, United Kingdom, Ireland, Japan, Germany, Holland, Australia, New Zealand, Singapore, South Korea, The Philippines, Mexico, and Brazil) and has thus far been translated into six languages: Japanese, German, Dutch, Spanish, Korean, and Portuguese. Wicked has amassed over $4.6 billion in global sales and has been seen by over 55 million people worldwide.

Based on the novel by Gregory Maguire, Wicked has music and lyrics by Stephen Schwartz, and a book by Winnie Holzman. The production is directed by Tony Award winner Joe Mantello with musical staging by Tony Award winner Wayne Cilento. Wickedis produced by Marc Platt, Universal Stage Productions, The Araca Group, Jon B. Platt and David Stone.