Is this ricotta chocolate chip treat the ultimate Philly cookie?

If you were to go by Philly’s national food reputation, you’d think the city had a major salt tooth, what with the sandwiches, pretzels, and scrapple. And you wouldn’t be wrong.

But don’t undersell Philadelphia’s penchant for sweets: We’ve got bakeries galore here, and they’re pretty much slammed all through December. There are pound cakes and yule logs and panettone to be had, sure, but the real star of the season is the Christmas cookie.

Philly’s holiday cookies come in all stripes, influenced by various baking traditions. There are cinnamon stars at Bredenbeck’s, alfajores from Jezabel’s, butter cookies from Danish Bakers, ginger snaps from Darnel’s, shortbread from Cake Life, linzer cookies from Essen, chocolate chips from Famous 4th Street, and many, many more.

In this panoply of cookies, is there one that is the most Philadelphian? My editor wanted to know.

It’s an almost impossible question to answer, but one thought did come to mind: the feathery ricotta cookies from Isgro Pastries. Slicked with a powdered-sugar glaze flavored with vanilla or lemon (and flecked with chocolate chips if the former), a pound of these puppies could easily disappear in minutes.

“It’s very light and airy,” says fourth-generation baker A.J. Isgro. “You feel like you can eat a thousand of them.”

Isgro was happy to share a recipe with The Inquirer for its cookie issue — just not the best-selling ricotta cookies. “I’m pretty sure my dad would kill me,” he says. “That’s his baby.”

Even if he were to share the recipe, it wouldn’t be quite right. The bulk of the Italian Market bakery’s recipes are hand-written on index cards and kept together in two ragged, flour-splotched binders that workers still consult day to day. But Gus Isgro, A.J.’s father, took care to guard some secrets.

“He would leave certain ingredients out so that if somebody were to want to get the recipe, then go somewhere else, if they tried to steal the recipe, it wouldn’t come out,” A.J. says of his father. (Why the suspicion? “He’s Sicilian.”)

» READ MORE: The best cookies from Philadelphia bakeries

The ethereal, pillow-soft texture sets Isgro’s ricotta cookies apart — and in some ways, they’re not true cookies. “This is more like a sponge,” the younger Isgro says as he pipes out generous dollops of pale batter onto a sheet pan. They bake up in minutes. He pulls them while they’re still mostly blond, then lets them cool before brushing them with lemony glaze. (The chocolate chip variety is drizzled with chocolate post-glaze.)

The glaze is another key to the cookie. It helps seal in its moisture, giving it a much longer shelf life than most sponge cookies. And it’s a perfect vehicle for flavor. Over the years, Isgro’s has infused the cookies with espresso, lavender, and orange — always gently, so as not to overpower the sponge.

Gus first whipped up these cookies about 25 years ago, his son estimates. They won honors at a Best of Philly contest some years ago. “About halfway through the competition, the judges came over and said, ‘It’s not even close.’ ”

In the years since, it’s become the bakery’s best-selling cookie and its second best-selling item overall. It’s only outdone by — what else? — Isgro’s cannoli.

Buy Isgro’s ricotta cookies by the box or tin, $27 and $64 respectively, at isgropastries.com/shop/cookies or at the bakery at 1009 Christian St.