Celia Sack is a voracious lover of cookbooks, but she’s also a collector of famous chefs. Sixteen years into owning Omnivore Books on Food, she has hosted everyone from the biggest cookbook writers to television personalities —  close to a thousand of them. 

For instance, on Thursday, Christina Tosi of Milk Bar will visit Omnivore for the second time, arriving from New York to squeeze into Sack’s postage stamp of a shop on a sleepy block of Noe Valley. There, Tosi will talk up her new book “Bake Club: 101 Must-Have Moves for Your Kitchen,” inspired by her insanely popular one-woman cooking show on Instagram Live. 

Considering that Tosi has 542,000 followers (and happens to be married to Will Guidara, co-producer of “The Bear” and the restaurateur behind New York’s Eleven Madison Park), Sack is expecting an overflow crowd to show up to the free event. (The 500-square-foot shop has room for only 60 people standing shoulder to shoulder.) 

“It’s like throwing a party,” she says with excitement and a tinge of weariness — the kind that comes from hosting these kinds of “parties” on repeat since 2008, when chef Eric Ripert of Le Bernardin swung by for a signing a few months after Omnivore opened.

Today, when authors like Ina Garten (who stopped by in October) are set to arrive, Sack puts folding chairs and a speaker on the sidewalk for those who can’t fit inside. To ease the pain of those waiting to get cookbooks signed, the gregarious Sack often pours shots: “It’s always some good Irish whiskey,” she says mirthfully. “I can’t skimp.”

After particularly popular signings — like the mob of fangirls who descended this month to meet Nicola Lamb, the British author of “Sift: The Elements of Great Baking” — Sack needs to decompress. She and wife Paula Harris usually retreat to an old farmhouse they own in Tomales. But she’s not complaining; none of this success was predictable. 

Her path began in 1998, when Sack and Harris started not a restaurant nor a bookstore but a dog-walking business. The duo opened the Noe Valley Pet Company, a pet store, on the corner of Church and Cesar Chavez the following year. A decade later, a teeny retail spot around the corner became available, and Sack decided to open Omnivore. Sack, a San Francisco native, had worked as a rare book specialist and had an antiquarian cookbook collection in the thousands. “They say so much about every part of the world, the culture, the geography,” she says of her obsession. Today, Omnivore has become known as much for its vintage cookbook selection as for editions hot off the press.

But it’s the author talks that draw crowds and enable Sack to break bread — or tacos, in the case of Madhur Jaffrey — with the industry’s biggest luminaries. The Indian legend, now 91, housed carnitas at La Taqueria after speaking about her cookbook “Vegetarian India.” Nigella Lawson, the gorgeous British cooking star who made licking her fingers into an art, enjoyed her own post-signing dinner at Sack’s Corona Heights apartment. Figuring it would be best to make Lawson something unfamiliar, Sack cooked up chicken pozole. When Yotam Ottolenghi visited, Sack opted for a green chile pork stew and cornbread; in turn, when Sack was in London, Ottolenghi had her over for “meatballs and a salad,” she recalled. These were recipes he was working on for his popular book “Simple.” 

However, the apex of her career was arguably the Ferran Adrià moment. In 2011, Sack and publisher Phaidon organized a talk at the Castro Theater with the world-famous El Bulli chef, then the reigning Spanish king of molecular gastronomy. The 1,400 seats sold out in 72 hours. “I was so nervous,” she says. “And that day it was pouring rain. I had to make so many trips over there with all the books loaded up in my pickup, which had formerly been used for our dog-walking business.” 

The stakes will be much lower this Wednesday, when chef-turned-actor Matty Matheson of “The Bear” comes to town, and Omnivore co-presents his City Arts & Lectures talk. Five hundred copies of his new book “Soups, Salads, Sandwiches: A Cookbook” will go to pre-sold ticket buyers, and Sack will be wrangling a tower of 300 to sell on-site, toted over in one her employee’s dog hair-free SUV. 

For most little booksellers, the Matheson appearance would be a very big deal, but for Sack it is business as usual. Curled up in a chair at her apartment, bare feet tucked beneath her, she reflects on the pinch-yourself life she has manifested. “Sometimes I can’t believe I made up this job for myself out of thin air. And it is actually working.”