Mueller, who is hosting the Creative Arts Awards portion of the Tony Awards with 2014 Tony winner James Monroe Iglehart, will star in the American Repertory Theater's world-premiere production of Sara Bareilles' musical Waitress.

Waitress will be directed by Tony winner Diane Paulus (Hair, Pippin), who will reunite with choreographer Mia Michaels (Finding Neverland) for the project.

“It being a new musical, I bet things are changing right now that I don’t even know about, but what I can say is that the music is stunning,” Mueller told Playbill.com on the Tony red carpet. “If you like  [Bareilles'] pop music or if you don’t even know her pop music, it sounds like her, but it sound like the characters. I think it’s really extraordinary work and I’m so excited to get in the room and work with her again and Sarah Bareilles and Diane Paulus and it’s just a very exciting project to me.”

Mueller, who also participated in a New York workshop of the musical, will play the central role of Jenna, who is described as "an inventive waitress trapped in a small-town diner and a loveless marriage. Pregnant and lonely, Jenna finds relief in making creatively-titled pies — and in a budding romance with an unlikely newcomer." “I think the thing I love about the character is kind of what I love about the whole piece,” she said. “It’s about a bunch of messy people. It’s about a lot of grey areas and tough choices and I think that’s kind of what life’s about. We all have wonderful, beautiful, glittery moments, like tonight, but most of life is trying knock through things and finding people you can do that with… finding a core of strength within yourself and sort of navigating life day to day, and I feel like that’s what this show is about.”

Mueller will begin performances Aug. 1.