In the dining room at Osteria Mozza, some kid is arguing with Nancy Silverton about food. It's mid-morning and with the restaurant closed for lunch, it's about the only time the room is empty. But already through the tall windows on Highland Avenue, you can see people lining up at their pizzeria next door. Silverton and the kid are standing at a marble table stacked with menus, and they're ripping one apart -- at least verbally.

Silverton is dressed stylishly, as usual, with an apron thrown over her designer duds. The kid has on a short-sleeved chef's jacket and he's got what looks like a large white dinner napkin wrapped around his head. Who is this guy? You might be surprised. Of course you know that Silverton and Mario Batali are the big-name chefs behind Mozza. But do you have any idea who's running the kitchen?

Matt Molina, a 29-year-old so baby-faced he looks as if he probably still gets carded when he orders a bottle of wine, is the executive chef at the two hottest restaurants in Los Angeles: the conjoined twins Pizzeria Mozza and Osteria Mozza.

While his bosses call the shots and get the headlines, it's Molina who makes sure everything works. He helps spin the dough in the pizzeria at lunch and he stands at the head of the osteria kitchen every night, checking each plate before it goes out.

It's Molina who works with Silverton and her co-owners Batali and Joe Bastianich developing the recipes and planning the menus. And then it's Molina who supervises the combined staff of roughly 75 cooks who serve the 600 diners who pass through the two restaurants every day. He does the payroll and he does the ordering.

Two demanding bosses

Wonderful as this opportunity might be for such a young chef, Molina is also very much in the hot seat. Not only is he running two of the most talked-about restaurants in town, with all the microscopic scrutiny that goes with it, he's also working for two very high-profile, very demanding bosses.

Not that it seems to bother him. Right now, he and Silverton are worrying about the arrista. A roast loin of Berkshire pork, it comes with a thick, highly seasoned fat cap -- the secret to its succulence and flavor. But that seems to be a problem for some diners. Molina has noticed that when plates come back to the kitchen with food left on them, it's most often the pork.

At first he and Silverton talk about changing the meat. But neither can bring themselves to do that -- they both love the pork. "We could change it but it just seems so right the way it is now," Silverton says. "Let's think about it and wait a little longer."

So they toss around ideas for changing the accompaniment -- maybe with a different presentation (and with a little more time to get used to it), diners will come around to their way of thinking.

Molina mentions that he's been getting great chanterelles. How about sautéing those? That idea bounces a couple of times, then Silverton suggests pairing the chanterelles with corn.

And what about fresh lima beans? Molina asks.

"Like a succotash?" Silverton says. "That would be good."

Molina pounces: "Last week I wanted to serve lima beans with my Sungold tomatoes and you wouldn't let me," he says, little brother baiting big sister.

"That's because we have too many tomatoes on the menu already," Silverton says. "I know it's summer, but every dish doesn't have to have tomatoes on it."

Chanterelles, corn and lima beans agreed on (but no tomatoes), Molina brings sous chef Chris Feldmeier out of the kitchen to give him preparation instructions ("wash the chanterelles really well in still water, just like morels, then spin them dry").

But after several tests, it's decided that the lima beans just aren't working. So, out they go. After a half-dozen other combinations are tried (even one with radicchio), it's decided it'll be just corn and chanterelles beside that lovely hunk of fatty pork.

Though It was the culinary marriage of the Bread Queen and Molto Mario that created the buzz, the actual fulfilling of both restaurants' promise falls in large part to Molina, a local boy who has cooked in only four restaurants in his career.

So far, he's passing with flying colors.