Mr. Hollis is far from the first amateur cook to snag a major book deal.
The Internet long ago democratized the notion of who can be an author, and publishers have sought to translate online followings -- from food blogs in the 1990s and 2000s to Instagram accounts in the 2010s -- into cookbook success.
"But nothing has converted quite as well as TikTok to actual sales," said Kristen McLean, an analyst at Circana.
Soon after the cookbook author Deb Perelman, 47, started the Smitten Kitchen blog in 2006, she received offers for short, quick-turnaround cookbooks for foods like holiday cookies.
"With TikTok people, I see them writing real, 300-page hard-core serious cookbooks," she said. "That, to me, is showing that the publishing industry realizes what they have in front of them."
And publishers are ponying up. TikTok creators are receiving the kind of advances that celebrity television hosts might get -- "definitely in the high six- or even over six-figure range," said Anthony Mattero, an agent at Creative Artists Agency who represents several TikTok creators.
"TikTok is the greatest selling machine right now," said Nadia Caterina Munno, 40, who parlayed her TikTok audience of 3.1 million followers into a deal for a cookbook, "The Pasta Queen."
Released last November, it debuted at No.5 on The New York Times "Advice, How-to and Miscellaneous" list. (She and the others interviewed for this article declined to share the exact amounts of their book deals.)
Ms. Munno's TikTok career took off with a video she posted in 2020 criticizing another creator's attempt at lasagna. Now, she said, "I am making more money than my husband. I am the breadwinner."
Beyond the money, publishing a cookbook carries prestige -- even for people who are already stars online.
"It was such an honor to do a book," said Jenny Martinez, 49, a Los Angeles mother of four who used to sell forklifts and now runs a TikTok account with 3.5 million followers; her cookbook, "My Mexican Mesa, y Listo!" will be released in April. A cookbook is "another level, and such an accomplishment for a publisher to believe in me."
But having millions of followers doesn't guarantee a blockbuster book, said Mike Sanders, the vice president and publisher of DK United States, which recently created a division devoted to books by online personalities.
Mr. Sanders spends time reading online comments, "just looking at the connection that the TikToker or social media creators have with the fans that might enable them to break through the noise," he said.
The comments on Mr. Hollis's videos convinced Mr. Sanders that "Baking Yesteryear" would sell. In just the past two years, DK United States, a division of Penguin Random House, has published six New York Times best-selling cookbooks by authors popular on TikTok.