This review was written for the festival screening of "Waitress."

PARK CITY -- Waitress" is a frustrating film.

It's not because it doesn't deliver -- it's a terrific Southern comedy that goes down as smoothly as a mint julep on a sultry afternoon.

Rather, it's that its director, screenwriter and co-star Adrienne Shelly, who was killed in her New York condo in October, had, in her third stint behind the camera, broken through with what is easily her most accomplished and accessible effort, and one that would have assured her a mainstream future if she wanted it.

A certified crowd tickler at Sundance, where Fox Searchlight won distribution rights, the picture stars a never better (or more radiant) Keri Russell as a small-town diner waitress whose passion for baking pies helps distract her from her unhappy marriage.

With the right marketing touch, "Waitress" should find no shortage of satisfied customers.

Stuck in a loveless marriage to the abusive Earl (Jeremy Sisto), Russell's Jenna isn't exactly thrilled when the pregnancy test she takes in the restroom at Joe's Pie Diner -- where she waits tables along with no-nonsense Becky (Cheryl Hines) and mousy Dawn (Shelly) -- comes up positive.

Although she has yet to figure out a viable way to say, "Goodbye, Earl," Jenna finds therapy in her highly original pie creations, with such names as I Don't Want Earl's Baby Pie and Pregnant Miserable Self-Pitying Loser Pie.

To further complicate matters, Jenna finds herself having a passionate affair with her new OB/GYN, the sympathetic but neurotic Dr. Pomatter (Nathan Fillion), which at least inspires her to create the Earl Murders Me Because I'm Having an Affair Pie (blackberries and blueberries smashed into a chocolate crust).

If "Waitress" was one of Jenna's pies, it would be a sky-high lemon meringue -- light, airy, not too sweet, with a tart, satisfying filling.

Shelly, who probably was best known as an actress for her performances in some of Hal Hartley's early films, has a real affection for her characters and their foibles, and judging from the work of her ensemble cast, it clearly was infectious.

Russell really shines here, displaying an affinity for the type of quirky comedy she has seldom had the opportunity to play onscreen.

While Hines, Shelly, Pomatter and Sisto also are fine, it's a particular hoot to see Andy Griffith coaxed back into pictures as Old Joe, the crusty but tender diner owner who urges Jenna to start fresh.

Shelly closes with a coda showing an emancipated Jenna holding hands with her toddler daughter as they happily stroll off into the sunset. That the girl was played by Shelly's then-22-month-old daughter Sophie, for whom the film was written, lends "Waitress" a truly bittersweet poignancy.

Fox Searchlight
A Night & Day Pictures presentation
Director-screenwriter: Adrienne Shelly
Producer: Michael Roiff
Executive producers: Todd King, Jeff Rose, Danielle Renfrew, Robert Bauer
Director of photography: Matthew Irving
Production designer: Ramsey Avery
Editor: Annette Davey
Costume designer: Ariyela Wald-Cohain
Music: Andrew Hollander
Jenna: Keri Russell
Dr. Pomatter: Nathan Fillion
Becky: Cheryl Hines
Dawn: Adrienne Shelly
Earl: Jeremy Sisto
Old Joe: Andy Griffith
Cal: Lew Temple
Running time -- 104 minutes
No MPAA rating