PERFECT COOKIE? RIPPLED DESSERT IS CRISP, SOFT, PHOTO-READY

Last fall, an aberrant chocolate chip cookie turned up in my Instagram feed. As wide as a salad plate and flat as a flounder, it appeared thin, but it was somehow layered with slabs of chocolate. Oddest of all, it was ringed, like a tree trunk — as if a chunk of chocolate had been dropped in the center and somehow made waves out to the edges. I assumed it was a mutant, posted by a troubled baker as a cry for help, and I kept scrolling.

But soon, the rippled cookie appeared again: as a one-off from a bread blog, then in 42burners, the Instagram account of Martha Stewart’s vast test kitchen. It showed up, insistently, as baker/ photographers like Ruth Tam kept posting it, crowing about the crispiness of the ridges and the softness of the centers.

I grew curious. It seems impossible that there’s anything new to say about basic chocolate chip cookies (a version from the pastry chef Jacques Torres, from 2008, is one we keep going back to, and for good reason). But a recipe that spreads across Instagram (and isn’t galaxy-, unicorn- or ombré-decorated) cannot be lightly dismissed.

When I spotted a new post that was simply a collage of photos of the cookie, I broke down. I tracked down the recipe, and then its author, Sarah Kieffer, who described the sacred rite of the ripples.

“It’s all in the pan-bang,” she said.

Here’s how it works: After the cookies have risen a bit in the hot oven, she pulls out the cookie sheet and bangs it hard on top of the stove, or on the oven rack. Just as a half-done cake falls in the center when bumped, the middle of the cookie collapses, pushing barelybaked dough out to the edges. She returns the pan to the oven and, at intervals, repeats the process, building up the crinkled rim that makes it possible to have both soft and crunchy textures in a single cookie. It is, I can attest, a leap forward in cookie technology.

It’s not clear even to Kieffer how the pan-bang came to her. But as a trained baker, she had the skills to develop a recipe around it that maximizes the ripple effect: making the cookies very large, chilling the dough balls before baking and using chopped chocolate instead of chips.

“I can’t imagine a better chocolate chip cookie,” said Kieffer, who makes and posts the cookies often, usually generating over 2,000 “likes” for each image. “But you never know what someone else will think of.”