LONDON — When you have made your bones by the freshness of your food, as Yotam Ottolenghi has, the change of seasons is a tense time. Gotta find a new fruit to go with the burrata, for example; maybe substitute delica pumpkin for the fast-receding peach. And why is the pastry suddenly so ... squidgy?

“Right now a big headache is croissants,” Ottolenghi said, standing in the gleaming white-tiled basement of his company’s showplace restaurant, Nopi (for North of Piccadilly), on the first morning of autumn.

Apparently, when the air is cooler, layers of flour and butter tend to huddle together. “They don’t separate enough, so that they become a bit gluey,” he said. “Not gluey, but stretchy rather than flaky.”

In the midst of an open larder stocked with tins and bottles of black and yellow mustard seeds, olive and sunflower oil, sherry and plum wine vinegar, pickled walnuts, coconut milk, Kitchen Klenz and Marmite (“Boost Your Bangers — Yum!”), Ottolenghi indicated a contraption called a proofer: a large metal cabinet that harbors dough like a ski-boot warmer.

“We need to increase the temperature and increase or decrease the humidity, I’m not sure,” he said. “I just know that the croissants are not as good. Normal people wouldn’t even know that there’s anything wrong with them. But I do.”

Ottolenghi, 46, may be exceptional, but he achieved this by catering to the common man, bringing far-flung zesty ingredients into the cupboard of the formerly timid English home chef.

Dark and telegenic, with a 6-foot-3 height elongated by regular Pilates sessions, he has a weekly column in The Guardian, four bustling canteen-delis scattered across this city (he has resisted opening elsewhere, citing control issues) and four best-selling cookbooks. These are known and widely knocked-off for their plain-spoken instructions, puffy covers and photographs he oversees himself, eschewing a food stylist as well as a personal one.

His new book about Nopi is somewhat more fancified, with gilded edges auguring the more complicated recipes within and credit shared with the restaurant’s head chef, Ramael Scully — marking the small Ottolenghi empire as an incubator of talent as well as croissants.

Scully, as he is known to all, was in the subterranean kitchen, too, a gentle giant toiling over a dish involving half-moons of roasted squash; tomatoes; a paste of ginger and garlic; dollops of Greek yogurt with lime and cardamom; and echalion, a hybrid of onion and shallot soaked in milk.

Ottolenghi had already had his porridge, having risen early with the two sons, Max, 2, and Flynn, 2 months, whom he is raising with his husband, Karl Allen.

“There’s not much sleep going on at the moment,” Ottolenghi said. “I dream of sleep.”

Ottolenghi was also fretting slightly about the return of truffle-flavored polenta sticks to Nopi’s menu, which had been removed in an attempt to free up the deep fryer for more experimental concoctions. Customers had complained.

“Now they’re back and everybody’s happy,” he said, rolling his eyes.

Plated and placed on a marble table, the squash was scrumptious, but there was hardly a moment to gobble it down before they had to go upstairs and outside, blinking in the sudden sun, to a silver Volvo SUV.

“Look at this day!” said Ottolenghi, who has a deep voice that slips into a Franck Eggelhoffer register when he is amused or excited. He wrestled with a car seat to make room for Scully, picked up a wayward pacifier that had tumbled to the pavement and settled in behind the wheel.

On the way to his test kitchen and main office, the conversation turned to sandwiches: He doesn’t like sugar in his peanut butter and, being from Jerusalem, sometimes substitutes tahini; while Scully, born in Kuala Lumpur, Malaysia, and raised in Sydney, Australia, retains a “fetish” for Jif and jelly on white bread. Then there is their taste in cinema.

“Seriously, the last movie I saw was ‘Minions,'” Ottolenghi said as soap bubbles floated past from the door of Hamleys, London’s FAO Schwarz. “I love animation. I sit there with Max and I think I have a better time than him. Especially, I love SpongeBob. Do you know SpongeBob? Of course you do.”

Scully chuckled softly. “I go for more adult content,” he said.

The Volvo was rolling past Regent’s Park, which Ottolenghi visits almost daily.

“I think it’s the most beautiful park,” he said. “Nicer even than Hyde Park.”

He drove into Camden Town, past the tacky market selling cheap clothes to tourist teenagers and the charming houses in their sherbet colors, and pulled into a parking lot outside the brick building beneath a railway arch that houses his test kitchen.

After the child safety lock was released, Scully followed Ottolenghi through another larder (Costco-size tubs of cream cheese) and up a staircase, where several efficient female employees were bustling around, making cupcakes with cappuccino frosting, French butter cookies called cat’s tongues and the like.

Here, concern arose about the speculoos — not a gynecological instrument but a Dutch confection baked in a log shape and scattered with almonds.

“A little dry, isn’t it?” Ottolenghi said, cutting off a piece as a train rattled the ceiling. “And the clove is still quite dominant.”

Though busy promoting “Nopi” over the next few weeks, he has already started on his next cookbook, which will focus on desserts.

“I think we’re going to call it ‘Sweets,’ but we don’t know yet,” Ottolenghi said. “We might not have the last ‘s’ there. We might have an exclamation point.”

Perhaps that would be a little Emeril Lagasse for the Ottolenghi brand, a visitor suggested.

“You’re right,” he said. “It’s gimmicky, too gimmicky.”

Maybe just plain “Sweet,” then — which, like the Mike Leigh movie, life is for Yotam Ottolenghi.