Flash/Supergirl Musical Includes Songs by Crazy Ex-Girlfriend Star, La La Land Duo

The upcoming musical crossover between The CW's "The Flash" and "Supergirl" will feature some noteworthy talent behind the scenes. Rachel Bloom, star of The CW's "Crazy Ex-Girlfriend," has written a song for the episode, as reported Tuesday by BuzzFeed. Additionally, the "La La Land" songwriting duo of Benj Pasek and Justin Paul have also written a song for the episode, The CW announced Tuesday.

Bloom's song will be titled "Super Friend," and performed by the leads of the two shows, Grant Gustin and Melissa Benoist. "I hopped on the phone with my old 'Robot Chicken' boss Tom Root and we brainstormed and, based on that brainstorm, I wrote up the song 'Super Friend,'" Bloom said in a statement to BuzzFeed, revealing that she "immediately" offered her services when she found out about the musical episode. "I am so excited to contribute more to the upward trend that is musicals in television and film. Music can be one of the most amazing and efficient forms of storytelling and character development. Also, it was really fun to write a comedy song for two superheroes."

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Pasek and Paul's song is titled "Runnin’ Home to You," sang appropriately enough by The Flash, Grant Gustin. Pasek and Paul wrote the lyrics to "La La Land" song "City of Stars," which has won a Golden Globe and Critics' Choice Movie Award, and is nominated for Best Original Song at the Academy Awards -- one of the award season front-runner's 14 Oscar nominations.

"Benj and Justin are the premiere song-writing duo of our time," "The Flash" and "Supergirl" executive producer Andrew Kreisberg said in The CW's press release. "Not only are they two of the most talented people Greg [Berlanti] and I have ever met, they are also two of the nicest. To have them be a part of our musical episode is beyond our wildest expectations. We hope everyone falls in love with the song they wrote for us as much as we did."

Bloom worked as both a voice actor and writer on "Robot Chicken," before co-creating and starring in "Crazy Ex-Girlfriend," which airs its second season finale this Friday. Pasek and Paul's previous TV work includes season two of NBC's "Smash."

"The Flash" and "Supergirl" musical crossover will start with a lead-in scene on the March 20 episode of "Supergirl," and continue in full on the March 21 episode of "The Flash." The episode will include musical numbers from “The Flash” stars Grant Gustin, Jesse L. Martin and Carlos Valdes; “Supergirl” stars Melissa Benoist and Jeremy Jordan; and “Legends of Tomorrow” co-star Victor Garber and “Arrow” regular John Barrowman; along with "Glee" alum Darren Criss as the Music Meister, the episode's antagonist.

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