How do streamlined stars like Catherine Zeta-Jones, Penelope Cruz and Nicole Kidman indulge in Tina Cassaday's rich, frothy shakes and still stay slim? The answer is that Cassaday's concoctions are slathered, not slurped. But the urge to ingest is understandable, considering the fact that Cassaday's line of "hair shakes" is made from ingredients exotic enough to make any chef drool. Among them: mangos, avocados, milk, champagne, cayenne pepper, kiwi and quail eggs ("Best source of protein in town," she declares). "People always tell me, 'Gee, I wish I could just drink that!' " says Cassaday, 43, who whips up the $425-a-gallon custom shakes in a blender in the Beverly Hills hair salon that bears her name. (Premade treatments are available in smaller sizes.)

A Dallas native, Cassaday has been styling hair since 1975, when she graduated from high school with a degree in cosmetology. But she didn't concoct her first potion until 1988, when she needed to get a bad dye job out of former Brady Bunch actress Eve Plumb's hair. Ultimately, a mix of fruit—grabbed from an ice-cream shop next door—did the trick. "It all built from there," says the twice-divorced Cassaday, whose 19-year-old son Justin is an actor. "I just had a gut feeling I was onto something real good." These days, her celeb clientele—which also includes actors like Tommy Lee Jones—can't get enough of her guiltless temptations. Jokes Jamie Lee Curtis, a longtime pal: "I always say I'm fixing my hair one banana at a time."