LOS ANGELES — The crowd is shoulder to shoulder at Joan's on Third. Power couples buy their toddlers "babyccinos" (steamed milk sprinkled with cocoa), and lithe women with "it" bags poise their forks over Chinese chicken salads. A voice from a loudspeaker interrupts the thrum: "If you are driving a white Jaguar parked in the back behind another car, please move your vehicle."

Just another morning at Joan's. What started as a tiny catering kitchen on Third Street, is, 14 years later, an L.A. institution. Former Gourmet editor Ruth Reichl breakfasts here when she's in town. So does Vogue's Andre Leon Talley. Actor Alexander Skarsgard reportedly comes for the meat loaf sandwiches and Kate Bosworth for the salads.

The 3,000-square-foot, spic-and-span cafe has a deli, bakery, cheese counter, and gelato bar. More than 2,000 customers a day come through the doors. The woman behind it all is Joan McNamara, a hip, cherubic, black-clad grandmother who drives a Mini Cooper and lives in a loft on Melrose. Soon to expand to a second location, she's still working the hot line making omelets. She's also the mastermind whose vision is manifested in every detail: the baby fig trees, vintage dolly tubs, private-label sauces.

The $13 boxes of dried pasta? She originally spotted those at a market in Bologna, Italy. The chandeliers are from London. Shelves are from an 18th-century convent in Albany, N.Y.

A glimpse of McNamara's kitchens, offices, and home reveals the inner workings of an obsessive who has steadfastly grown a company that now employs 110 people. And if all goes as planned, a Joan's on Third will open in a former post office in Studio City this year.

The daughter of Czech immigrants, McNamara grew up in New Jersey, moved to Manhattan in her 20s, and worked for designer Paul McCobb, then with chef Dione Lucas running her cooking school and a restaurant called the Egg Basket.

After moving to L.A. with her late husband, McNamara stayed home with her daughters, Carol and Susie, who've helped her run Joan's since graduating from college. Carol runs the catering operation, and Susie the marketplace. It was their idea to call it Joan's on Third. "I always wanted something clever," McNamara says. "I would read the dictionary every night to find the one right word … ."

Despite all the traffic, nothing's ever out of place. "Oh, that drives me crazy," she says of a kaput lightbulb in a chandelier. Employees say they take the lead of McNamara, who straightens out-of-place bottles of imported olive oil, makes sure the deli platters are always full, tidies the bathrooms. She takes no days off unless she is traveling.

Customers love McNamara too. "We come here No. 1 because of Joan," says Richard Ingold, a regular who meets friends here every day. He's one of two people for whom Joan's has allowed a private party, the other being Donna Karan. But one couple did marry here, a quiet ceremony at a back table to commemorate the place they met.

The cafe is open from 8 a.m. to 8 p.m., but the commercial kitchen next door runs from 5 a.m. to midnight. On the door to McNamara's office hangs a sign that says "Bureau de Chef." The wall behind her is lined with cookbooks. When Yotam Ottolenghi, owner of McNamara's favorite London cafe, stopped by for a book signing, he turned her on to a website called Eatyourbooks.com, which indexes recipes. She has 69,477 recipes from seven blogs, 315 magazines, and 468 books.

And those are just from her office. Her high-ceilinged loft is filled with cookbooks too. Along with particulars collected from Europe and antiques stores: Cherner chairs, an Italian credenza, a marble-topped candy-making table, dishes from the south of France. In her closet are her all-black clothes, including the long black skirts she likes to wear. "A friend said I should number them," she says.