Sept. 24 (Bloomberg) -- Two years after opening an unassuming fieldstone restaurant named the French Laundry in Yountville, California, Thomas Keller dismissed the idea of opening another venue.

``If this is Thomas Keller's cuisine,'' he told the New York Times in 1996, as the restaurant was beginning to garner national attention, ``how can you have it in two places?''

Today you can sample it in five: two upscale French- influenced restaurants, two bistros and an American family-style spot. He also oversees two bakeries and a catering operation. He wants to open an inn, butcher shop and burger joint. His frozen- food line should soon hit retail shelves.

Some observers wonder whether Keller's reputation for consistently superlative cuisine, earned with the French Laundry and fortified three years ago with New York's Per Se, can survive the expansion.

``You have to expect that with your attention that diverted, you're not going to be able to keep the quality,'' said Ruth Reichl, the bestselling food author who wrote an influential early review of the French Laundry in the Times. ``I just don't think that's possible.''

Others argue that Keller, 51, can execute at the highest levels across an ever-widening empire. He is the only U.S. restaurateur and one of two worldwide to earn Michelin's top rating of three stars for two restaurants (the other, Alain Ducasse, has done so for three). Even Keller's Bay Area bistro, Bouchon, earned one, matching Alice Waters' culinary landmark Chez Panisse.

``It's definitely the obsession for perfection that drives him,'' said Daniel Boulud, chef and founder of New York's renowned Daniel, who oversaw Keller earlier in his career. ``He is certainly the best American chef you have today.''

Consulting for a Rat

Keller served as a consultant on Pixar's recent foodie film ``Ratatouille,'' training the crew on fine dining concepts and inventing the dish served in the pivotal scene. The movie features a rat that uses his refined palate to revive the reputation of a late French chef's restaurant while others attempt to use his likeness to sell frozen foods.

Keller himself designed and placed his name on two real- life frozen dishes for FiveLeaf, a unit of Cuisine Solutions Inc., based in Alexandria, Virginia. The company will soon begin pitching one, Mac and Cheese Lobster with Orzo, to retail stores, said Lillian Liu, the company's marketing manager.

Keller also is planning to open a meat shop, Bouchon Boucherie; a 20-room auberge, the Inn at French Laundry; and a hamburger and wine joint, Burgers and Bottles.

Staff Opportunities

He said the main reason he changed his mind about pursuing additional opportunities was his staff. By providing advancement possibilities within his organization, he can retain and motivate his employees.

``To maintain the consistency and quality of the staff, you have to give them opportunities,'' Keller said in an interview.

That, in turn, helps ensure the integrity of the product. The standards first honed at the flagship were carried over to new ventures in large part by plugging in the same employees. French Laundry alums Jeffrey Cerciello and Jonathan Benno, for example, are now the executive chef of Bouchon and chef de cuisine at Per Se, respectively.

Keller also takes his time planning new businesses, notably spending three years on Per Se. In addition, he took the unusual step of shutting down the French Laundry for 4 1/2 months before opening the New York restaurant, temporarily moving much of his existing staff there to ``indoctrinate that group,'' he said.

`Questioning the Magic'

Whatever the precautions, expanding a fine dining operation carries risks, industry observers say. The sheer number of restaurants can make the experience at any one seem less special, or tackling too many operations can stretch an owner's attention to the point that something gives.

``When you expand like that, certainly beyond restaurants, which he's very good at, into other things, which we don't know if he's good at, of course you'll always risk diminishing the quality,'' said Michael Ruhlman, who co-wrote ``The French Laundry Cookbook'' with Keller.

In addition, slipping quality at the flagship or a disappointing premiere can diminish the reputation and buzz surrounding the other establishments.

``They have to be focused on their flagship,'' said Jean- Luc Naret, director of the Michelin Guide. ``Otherwise they will lose all the other parts.''

Slipping Reputations

History is littered with hundreds of acclaimed chefs whose cuisine suffered as their businesses grew, Reichl said. They can lose stars, customers, venues or reputations.

She declined to cite an example. Michael Bauer, executive food and wine editor at the San Francisco Chronicle, pointed to Wolfgang Puck.

The Austrian chef earned glowing reviews for Ma Maison and Spago in Los Angeles in the 1970s and 1980s. He's now better known for his gap-toothed grin in the frozen-food aisle.

``Once you get into frozen food and pizzas, your fine dining brand gets a little fuzzed out,'' Bauer said.

Some have already detected worrying signs in certain corners of Keller's operation. Food writer Mimi Sheraton, in a New York Times article last summer, described Keller's Bouchon bistro in Yountville as ``jam-packed and wildly noisy.'' She recommended avoiding the onion soup, pate de campagne, roast chicken and gigot of lamb.

Uneven Service

Bloomberg's own trips to Bouchon and Keller's newest restaurant, Ad Hoc, were notable for consistently impressive cuisine and curiously uneven service.

The Ad Hoc busboy could list the key ingredients in the seared rack of lamb's savory crust, yet the wine took more than 10 minutes to arrive and water refills failed to appear throughout the entrees. When the runner did come with a pitcher, after being asked, he set it down on the table and turned his back on two empty glasses.

Bauer wrote earlier this month that his latest visit to the French Laundry wasn't as ``remarkable'' as a meal several years earlier. Still, he disputes assertions that the flagship has lost its edge and said he believes Keller will maintain his reputation with the new ventures.

Keller himself acknowledges that he takes a gamble with every new enterprise. Yet he insists he hasn't and won't pursue anything that threatens an existing restaurant. Ultimately, he believes his success in the future will rely on the same thing as his success in the past: his employees.

``It's really all about staffing, hiring the right people and training them correctly,'' Keller said. ``They're the ones who make it happen every day.''

To contact the reporter on this story: James Temple in San Francisco at jtemple@bloomberg.net

Last Updated: September 24, 2007 00:04 EDT