On a recent morning in the Inner Richmond, outside tiny Arsicault Bakery, a line stretched down the block. Word traveled through the crowd, telephone-style, that it had run out of croissants, and one man expressed doubt that he’d get any pastries at all.

It was 10 a.m.

Owner Armando Lacayo eventually came out to confirm this, looking a little worn. “I’m very sorry, but I don’t think we’ll have anything left for you,” he said to those at the back of the line, his French-accented voice full of regret. “Believe me, I’ll work even harder tomorrow.”

Arsicault was an unassuming bakery until two weeks ago, when the national food magazine Bon Appétit crowned it the best new bakery in America. The editors described its signature item as “a croissant that’s simultaneously so preposterously flaky it leaves you covered in crumbs, so impossibly tender and buttery on the inside that it tastes like brioche, and so deeply golden that the underside is nearly caramelized.”

Et voilà, people came from far and wide to try this golden creation. And the bakery is still trying to figure out what hit it.

Lacayo, 49, didn’t set out to open the country’s best bakery. He just wanted to make good-tasting croissants, the kind he’d grown up eating during his Parisian childhood. His great-grandparents had owned a bakery in the suburbs of Paris, and his grandfather had worked in the bakery until his 20s, when he switched to a non-baking career. He still taught Lacayo the qualities of great baked goods at an early age.

Lacayo also has an innate interest in food: He can remember the exact moment he had his first kouign amann — a round, sweet puff pastry cake — on a family vacation to Brittany when he was 13. He says he “could draw a map of France with the places I’ve had a really good croissant.”

For most of his life, Lacayo’s vocation lay elsewhere, in front of a computer, managing mutual funds. His career as a baker began 15 years ago when he lived in New York and couldn’t find a croissant to his liking. Armed with a cookbook and his taste buds, he set to laminating dough for croissants in the heat of August, with no air conditioning — tough conditions even for an expert.

But he persevered, and he continued baking when his job took him to Kansas City, Mo., and then Mountain View.

“Eventually I got something that looked like a croissant, and much later, something that I was almost satisfied with, and even later, something I wanted to share,” he said.

Three years ago, Lacayo decided he’d spent enough time at a desk and went to pursue his first love. He enrolled in a bread course at the San Francisco Baking Institute and started to look for bakery space. He found it in a 1,500-square-foot building at Clement and Arguello, a former bakery that had just enough room in the front for a counter and a few tables up a set of stairs.

He named the business after his grandparents’ bakery, Arsicault Boulangerie, and decorated the small front room with a photograph and a vintage delivery wagon from their shop.

Since its doors opened in April, Arsicault had been the kind of neighborhood bakery that had gotten good reviews but not transcended to the hype of, say, B. Patisserie in Pacific Heights. Then, two Wednesdays ago, Lacayo was in the bakery when he got a call from a friend congratulating him on the Bon Appétit nod. It took him by surprise.

A crowd was waiting the next morning when he opened; news crews arrived later. Production, which had hovered around 500 pastries a weekend, nearly doubled, and he’s still selling out by midmorning, several hours before his official closing time.

Lacayo is working to hire more bakers. Meanwhile, he’s sorry when he has to turn anyone away — and when he sees people peering in the windows after he’s closed for the day. “Sometimes people come from pretty far away,” he said. “I wish I had something for them.”

On another recent morning, this reporter arrived a few minutes before Arsicault opened at 7 a.m. Nearly 40 people were standing in line, bundled against the foggy morning. As we inched slowly toward the door, I wondered, exactly, what we were all waiting for.

It couldn’t be just an exceptional croissant; no matter how great this one was, there’s not that much room for improvement on the nearly perfect specimens at places like Neighbor Bakehouse, Tartine, Fournée in Berkeley and the Bay Area’s other excellent patisseries. And the wait at Arsicault made even Tartine’s famous line seem negligible.

So what had drawn the crowd — bragging rights? The sense of accomplishment? The chance to taste the best new croissant in America and assess it on one’s own terms? Was that even possible anymore?

There’s a scene in Don DeLillo’s novel “White Noise” when the narrator and a fellow professor pay a visit to the “most photographed barn in America.” They stand in silence, watching people take pictures of the barn.

“No one sees the barn,” the colleague says finally. “Once you’ve seen the signs about the barn, it becomes impossible to see the barn. … We can’t get outside the aura.”

Here we were, inside our own sugar-scented aura. The charming neighborhood bakery that Bon Appétit’s editors had stumbled on had momentarily ceased to exist, and in its place was a much-hyped croissant factory that caused otherwise reasonable people to wait in a 30-minute line at 6:55 on a chilly morning.

We weren’t waiting for breakfast. We were waiting to see whether this experience was worth it.

So was it? Let’s say that it’s almost criminally unfair to judge a place a few days after a tidal wave of unexpected publicity, though of course that’s what everyone was doing. The plain croissant was good: architecturally sound and buttery tasting, though it was a little pale, not the burnished gold one might hope for, and a little doughy in the middle. (This bears repeating: They doubled production in a week. Pre-Bon Appétit, the croissants were much darker, with a more developed interior structure.)

The pain au chocolat was better, with distinct layers and a glossy finish. I liked the kouign amann best. It was flatter than others around the region, shaped more like a spiral than a crown. Lacayo modeled it after a version he’d eaten in the Breton town that claims it invented the pastry, and they know what they’re doing: The flatness meant increased surface area for sugar caramelization, and it was flaky and buttery in all the best ways.

Was the wait for Arsicault worth it? Perhaps — in a few weeks, once the crowds and kitchen reach some sort of equilibrium. It would be worth returning then not only to try the croissants anew, but also all the pastries they no longer have time to make: lemon and chocolate tarts, quiche, pailles (delicate puff pastry and jam sandwiches).

For now, Lacayo is putting his head down and trying to make as many pastries as possible in the face of this unexpected windfall.

“It’s really incredible. I don’t know what to say. I really believe in my product, so I’m glad that many people agree with me,” Lacayo said. “It’s almost like I have a responsibility now to make it available. I’m working on it.”

Anna Roth is a San Francisco freelance writer. Email: food@sfchronicle.com Twitter: @annaroth

Arsicault Bakery

What: Plain croissant ($3.50), chocolate croissant ($4.50), kouign amann ($4). Currently, the bakery is imposing a three-item limit to prolong the inevitable sellout, but that can’t last forever.

Where: 397 Arguello Blvd. (at Clement Street), S.F. (415) 750-9460.

When: Tuesday-Friday 7 a.m.-1 p.m., Saturday-Sunday 8 a.m.-2 p.m., Monday 8 a.m.-1 p.m. Get there right at opening for the best selection; pastries have been selling out by 10:30 to 11 a.m.