Sara Bareilles / Photo by Gina Ciliberto

Sara Bareilles / Photo by Gina Ciliberto

Last week, Sara Bareilles and select members of the cast of Waitress visited Barnes & Noble on 86th Street to discuss the musical and perform a few numbers from it. Sara composed the musical, which is now a hit on Broadway.

Jessie Mueller (Jenna), Drew Gehling (Dr. Pomatter) and Dakin Matthews (Joe), all sang at this event. However, the real treat was hearing Sara Bareilles emcee the brief show and spill some secrets from the process of composing the score for Waitress.

One of the first things she admitted — while beaming with pride and excitement — was how hard the show had been to put together. She started writing music and lyrics for the show four years ago, but the score had been transformed in the time since.

Jessie Mueller / Photo by Gina Ciliberto

Jessie Mueller / Photo by Gina Ciliberto

As Sara put it: “We came away from [an early] production realizing we weren’t quite getting enough of Jenna’s backstory, and we weren’t quite understanding exactly her relationship to her pie-making and why her history was so involved in these recipes.”

After “reimagining” various songs — and writing one (“Bad Idea”) to a “Bavarian March” rhythm via Garage Band — Sara has created a Broadway show with which she’s “deeply in love.”

Waitress has absolutely changed my life,” Sara said. “It has been life-changing and life-saving in so many ways.”

She’s also gotten to know the cast on an intimate level. She’s seen Dakin Matthews’ card set, of which each card contains one of his roles. And she gushed about Jessie who “brought so much grace and so much humility and vulnerability to this role.”

“It is one of the incredible pleasures of my life to get to know and get to work with Jessie Mueller,” Sara said.

Sara Bareilles / Photo by Gina Ciliberto

Sara Bareilles / Photo by Gina Ciliberto

If the show was once difficult and stress-inducing, Sara showed no signs of it in her demeanor that afternoon. She high-fived the cast and clapped along giggling while they sang — and it turns out Bavarian marches are actually pretty catchy.

It was no surprise, then, when Sara remarked that the show altogether has been “absolutely magical.”

“It’s been a myriad of emotions, Sara started. “But, ultimately, to have this show, to have this moment to celebrate this music and these incredible performers, it’s just something that I’ll never get over and never forget.”

Waitress runs Tuesday through Sunday at the Atkinson Theater on West 47th Street. To date, it has been nominated for four Tony awards, including Best Musical.