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.

But soon, the rippled cookie appeared again and again, even in the Instagram account of Martha Stewart’s vast test kitchen. Posters crowed about the crisp ridges and soft centers.

I grew curious. It seems impossible that there’s anything new to say about basic chocolate chip cookies. But a recipe that spreads across Instagram cannot be lightly dismissed.

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 oven, she pulls out the cookie sheet and bangs it hard on top of the stove, or the oven rack. Just as a half-done cake falls in the center when bumped, the middle of the cookie collapses, pushing barely-baked dough to the edges. She repeats the process at intervals, 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 usually generates over 2,000 “likes” for each image. “But you never know what someone else will think of.”

Giant Crinkled Chocolate Chip Cookies

• 2 cups all-purpose flour
• 1/2 teaspoon baking soda
• 3/4 teaspoon salt
• 1/2 pound unsalted butter (2 sticks), room temperature
• 1-1/2 cups sugar
• 1/4 cup packed light or dark brown sugar
• 1 egg
• 1-1/2 teaspoons vanilla extract
• 2 tablespoons water
• 6 ounces bittersweet chocolate (about 60 percent cacao solids), chopped into coarse pieces, creating bits and shards

Adjust an oven rack to middle position. Heat oven to 350 degrees. Line 2 baking sheets with foil, parchment or nonstick baking mats.

In a small bowl, whisk flour, baking soda and salt.

Using a mixer, beat butter on medium until creamy. Add sugars and beat on medium until light and fluffy, 2 to 3 minutes. Add egg, vanilla and water; mix on low to combine.

Add flour mixture; mix on low until combined. Mix in chocolate. (At this point, the dough can be refrigerated for several hours or overnight.)

Form dough into 3-1/2-ounce balls (a heaping 1/3 cup). Place 4 balls equal distance apart on prepared pan. Transfer to freezer for 15 minutes. After first baking sheet goes in oven, put second one in freezer.

Bake 10 minutes, until cookies are puffed slightly in center. Lift baking sheet and let it drop down against oven rack, so edges of cookies set and insides fall back down. (This will feel wrong, but trust me.) Bang it down, if necessary, to make centers fall.

Let bake again 2 to 3 minutes more, until cookies puff up again, then repeat lifting and dropping pan. Repeat every 3 minutes, to create ridges around edges of cookies. Bake 16 to 18 minutes total, until cookies have spread out and edges are golden brown. Centers should be much lighter and not fully cooked.

Transfer baking sheet to rack; let cool completely before removing cookies. Repeat with remaining cookies. Makes 10 large cookies.

Nutritional information unavailable.