“Sugar, butter, flour.” A woman’s voice carries across a dimly-lit diner minutes before the room is jolted to life by the arrival of hungry customers.

The voice belongs to Jenna, the mastermind behind the coveted desserts at Joe’s Pie Diner and the star of the musical comedy “Waitress.” Those three ingredients form the basis of her bakes, but they’re also her lifeline while she tries to stay afloat in a joyless marriage. She’ll reprise the sing-song line throughout the show, almost like a prayer. “Sugar, butter, flour, don’t let me down,” she muses early on.

Set in the American South, “Waitress” takes on difficult subject matter — abuse, unexpected pregnancy, infidelity — but Northern Stage’s production, which opened last weekend in White River Junction, proves to be as sweet and enticing as its protagonist’s most decadent creations.

When we meet Jenna, played by Brianna Kothari Barnes, she seems resigned to her life with the no-good deadbeat Earl. But when diner owner, Joe, learns she’s pregnant, he encourages Jenna to enter a local pie-baking contest with a $20,000 cash prize that would allow her to ditch Earl for good.

Upping the stakes, Jenna launches into an affair with her obstetrician Dr. Pomatter (Michael Evan Williams), a Connecticut transplant with a neurotic personality and a spouse of his own.

What could be a maudlin tale is constantly brightened by a roster of poppy musical numbers, courtesy of Grammy Award-winning singer-songwriter Sara Bareilles, who wrote the music back in the early 2010s and starred as Jenna on Broadway in 2017. The musical is based on a 2007 film starring Keri Russell.

Kothari Barnes, who’s based in New York City, shares Bareilles’ vocal chops. “Waitress” marks her debut at Northern Stage and her portrayal of Jenna leans into the character’s weariness. Her face bears a tension that rarely lifts, save for those quiet moments when she’s baking, a skill she learned from her mother.

Nonetheless, the world of “Waitress” is one filled with delight, including a cohort of dancing customers, and Jenna’s jocular best friends Becky (Rae Agwe) and Dawn (Caitlin Kinnunen).

The ensemble also brings a focus that elevates the production as a whole, especially in the highly choreographed group number “Opening Up.” Even at the preview I attended, every set change and musical cue was crisp and polished, a testament to the careful eye of Carol Dunne, the show’s director and the artistic director at Northern Stage.

“Waitress” embraces its comedic nature, and every actor gets their fair share of witty material to play with. Perhaps the most successful among them was Jacob Tischler, who plays Ogie, an earnest tax auditor Dawn met on a dating app who drives a subcompact Toyota Yaris and adores his mother. His performance in a particularly earnest scene at the diner involving a bouquet and some very stiff choreography was an obvious highlight.

Comedy didn’t look as good on some of the other characters, however. It was hard to know what to make of Earl, for instance, who sometimes postured as an oafish jester, a cruel manipulator or a groveling child. Perhaps the variation was intended to give him depth, but his disparate modes didn’t quite gel for me, which is more a critique of Jessie Nelson’s writing than of Thom Miller’s performance.

Dr. Pomatter and Jenna’s chemistry was also somewhat elusive. It seems that his kindness and enthusiasm for her baking, which Earl distinctly lacked, was enough to draw her in.

The bond between Jenna and her co-workers, however, is impossible to deny. We learn that they have fraught relationships of their own, and it’s through observing their lives that Jenna starts to wonder if she should aspire to more than being “happy enough,” as the cook, Cal, puts it.

The play invokes a subtle tension between acceptance and complacency that each character must navigate for themselves. In the end, Jenna is able to chart a new course for her life. She remains among her friends, without whom she might not have had the courage to act, but her fate seems more her own. It’s a kind of American dream, and viewers can decide how close it comes to reality.

Northern Stage’s production of “Waitress” runs through April 13. For tickets ($27-$97) and more information go to northernstage.org or call 802-536-1769.

Marion Umpleby can be reached at mumpleby@vnews.com or 603-727-3306.