Transcript for Sara Bareilles on making her Broadway dreams come true
Sara Bareilles has been a pop superstar for years, so it's hard to believe that her childhood dreams are just now coming true. But that's what she's saying about her debut as a composer and actress in her Broadway musical "Waitress." ABC's gio Benitez takes us behind the scenes of the smash hit show. The first time I saw the marquee I completely lost my mind. ??? I want to see you be brave ??? Reporter: Hit singles like "Brave" may have catapulted Sara Bareilles to the top of the charts, but for the multigrammy nominee this is where her childhood dreams are finally coming true. There it is right there. Starring Sara Bareilles. I know. That's me. Reporter: Her name shining bright under those Broadway lights. To be as cheesy as I can be, it's like childhood fantasy coming true in a way I would never have imagined. Do you feel like a Broadway star? Oh, my god, no. No. Crazy. Stop. But you never felt like a pop star either. No. I'm just a schmoby from the sticks. Reporter: All a piece of humble pie from the current lead actress in one of the hottest tickets on Broadway, "Waitress: The musical." ??? Sugar, butter, flour ??? ??? don't let me down ??? in the show she plays Jenna, a small town waitress full of big dreams and in search of a new life, a better life far from her abusive husband. This would mark her second role in what has become a passion project for the singer-songwriter who first left the world of pop to join the "Waitress" production as the lead composer. I was getting fatigued of the cyclical nature of being a pop artist where you write a record, record a record, go on tour, promote, come home, do it all again. So I just was ready to work on something different. ??? It's not easy to know ??? Reporter: For 3 1/2 years she worked tirelessly to bring the show to life. One song at a time. ??? She used to be mine ??? I rewrote the opening number 40 times. Wow. Like I wanted to absolutely tear my hair out and throw people across the room. It was so frustrating. But that pressure cooker is I think actually kind of an exciting place to be. ??? For a chance to start over ??? Reporter: Those catchy and heartfelt show tunes like "She used to be mine" would lead to a Tony nomination. In the past decade a constellation of accomplishments from a best-selling book to a list of hit songs that would lead to six grammy nominations. Singles like "Love song." ??? I'm not gonna write you a love song ??? and "Brave." ??? I want to see you be brave ??? This Anthony elm the perfect example of how she's not afraid of getting personal. "Brave" is a love letter to one of my best friends. A dear friend of mine who was struggling with coming out. I just wanted to say to them like it's okay to be yourself. There's love waiting for you. Reporter: And now it's Bareilles herself experiencing that love. Eight pformances a week. Stepping in to fill the shoes of Tony winner Jesse muller. Completely totally intimidating. Jesse is a singular talent. Stepping out here for the first time was unreal. I can imagine. What were you tnkg when you just first looked out here? Just -- I mean, I can't say it because it's network television. But oh, my gosh. Like oh, my god. It's real. Reporter: And it's not going unnoticed. Bareilles holding her own with some of the biggest names on Broadway. And it just so happens for you that this is a time when you have Glenn close there. My arch-nemesis. Bette midler. I know. Incredible humans on Broadway. Do you at times feel like you're pretending on Broadway? Or even pretendinghen you're writing songs? I don't want to fake anybody out and make them think I'm a great actress. What I want to do is come and do my best work and work really hard at being great at honoring the craft. ??? Heartbeat ??? That hard work paying porch during her first week as lead actress the show bringing in more than a million dollars in ticket sales, a record for this theater. This show is just becoming comfort food for people, and they really love the story. Hello, Jenna. Reporter: The show, based on the 2007 film "Waitress" starring Keri Russell. How's the bad husband? Excuse me, I feel like I'm going to be sick. Reporter: It's a very musical movie, though. There are movies that just sort of sing a little bit, and this to me is one of them. Reporter: The indie film written and directed by Adrienne Shelley, who would also star in the film. Shelley was tragically murdered in 2006, right before the release. Reporter: We get to carry on her legacy. Reporter: Another example of the sisterhood behind the project, "Waitress" would become the first Broadway show with an all-female creative group. And while other musicians, Cyndi lauper and Carole king, have brought their music to the Broadway stage, Bareilles joins the ranks of sting and Billy Joe Armstrong. ??? Don't want to be an American idiot ??? As both composers and act rorsz. ??? Don't want a nation under the new media ??? In their own Broadway show. Do you think you're going to continue in that role on Broadway possibly doing other shows? I certainly would love to revisit the composer hat and write another show. Reporter: An opportunity she says that has completely allowed her to change her life. The people that I'm close to, the things that I do professionally, my colleagues, my best friend, my boyfriend, like all of these things have come to me because of this show. And it's really beautiful. Reporter: For "Nightline" I'm gio Benitez in New York.
This transcript has been automatically generated and may not be 100% accurate.