He also needed a pastry chef who understood that it would be unproductive to take an oppositional stance toward the vision of Mario Batali, Joe Bastianich and Lidia Bastianich, Del Posto’s owners. “We wanted someone who was willing to assimilate,” Mr. Ladner said. More precisely, the pastry chef had to be open to learning at the elbow of Ms. Bastianich.

“Brooks was very warm to the idea of being influenced by her,” Mr. Ladner said. “The two previous pastry chefs were not into that dialogue at all, which made it really hard.”

Since Ms. Bastianich’s philosophy hinges on simplicity, she and Mr. Headley “dance well together,” as she puts it.

Image Mr. Headley on the drums in 2013 with his band C.R.A.S.H. Credit Jason Fulford

“As a chef, you can exalt nature,” she said. “When nature gives me the perfect apricot and I have not smothered it with something else, I feel the best. And I think he does that, too.” Besides, as Mr. Headley reminds readers countless times in “Fancy Desserts,” the punk-rock shtick is sort of a cover-up for his real identity. Underneath it all, he views himself as an Italian grandmother, and he credits women with teaching him everything he knows.

“I am a femininity embracer,” he said.

Such is the nature of Mr. Headley’s macho-avoidance that Kerry Diamond, one of the founders of the food-and-femmes-focused Cherry Bombe magazine, identified him as “the first guy we ever let write a piece for Cherry Bombe.” She sees “Fancy Desserts” as a game-changer. “Cookbooks have gotten so boring and formulaic,” Ms. Diamond said. “Brooks’s cookbook is like no other cookbook.”

In spite of a full name — Brooks Oliver Headley — that seems like something plucked from an Edith Wharton novel, he was raised in the suburbs of Baltimore by a mother with roots in Calabria. “Italian — that’s what I know,” he said.

He never went to culinary school. When his musical pursuits hit a speed bump in 1999, he bumbled into a job at Galileo, a restaurant in Washington. “It wasn’t like I wanted to be some fine-dining pastry chef, because I had no idea what that was,” he said. “I had no idea what a tuile was. I didn’t know how to spell tuile.” (It’s a fragile decorative wafer.)