Talk about misleading advertising! This clumsy comedy fails on almost all fronts, and here's why. Sarah Michelle Gellar, who plays TV's "Buffy the Vampire Killer," and Sean Patrick Flannery, who plays TV's "Young Indiana Jones," both need a truly stellar vehicle to make the crossover from the small screen to movies - and this isn't it. She plays an inexperienced chef and restaurant owner who, magically, is able to cook her sensuous passion into glorious cuisine after she meets this man of her dreams. This idea worked for Mexico's erotic, enchanting "Like Water for Chocolate," but it falls like a soggy souffle here. According to the contrived script by Judith Roberts, briskly but routinely directed by Mark Tarlov, Gellar inherits a failing 70 year-old TriBeCa restaurant, the Southern Cross, from her mother. Playwright Christopher Durang plays a cab driver Cupid as he, magically, utilizes an elusive crab to engineer a "cute" meeting between Gellar and Flannery in a Manhattan Farmer's Market. Flannery's a self-absorbed retail executive in charge of opening a trendy new restaurant called Jonathan's in Fifth Avenue's tony Henri Bendel, and his temperamental French chef is giving him grief. Can you guess what happens? Gellar's Crab Napoleon enchants him, but the standard ingredients are all measured out: no surprises, no spice, no zest, no originality. Only some stalwart supporting actors - Betty Buckley, Dylan Baker, Larry Gilliard Jr., Patricia Clarkson - are trying the best they can. And, if you've seen "You've Got Mail," you'll find the plot similarities striking. Not that it's not pleasant. It is - but so bland that, if you go, you'll soon crave something else. On the Granger Movie Gauge of 1 to 10, "Simply Irresistible" is a quite resistible 3. Back to the kitchen for something with more gusto