TASTE: Glaser's Bake Shop's Black-and-White Cookie

I was skeptical of the black-and-white cookie. There was something obscene about their nearly half-foot diameter, the chocolate and vanilla icing: it was like having your cookie at eating it too. They always seemed to lurk near the beef jerky, stifled by Saran wrap, or beside dry-looking pastries in Italian bakery windows. But once I learned they were an iconic New York City treat, I had to find out what all the fuss was about.

So I headed to Glaser's Bake Shop, a century-old Upper East Side institution, and ostensibly the progenitor of the black-and-white cookie. Owner Herb Glaser couldn't confirm this; indeed, he knew very little about the origins of his shop's yin-yang confection. He did reminisce about having two for dessert when he got home from school ("I was a fat kid") and eating the white half first "to save the best for last." He told me Glaser's makes the cookies fresh each day, using a cupcake batter thickened by flour, which creates the cookies' signature cakelike texture. Both icings have a fondant base, spread on with a spatula: you do the white first, let it set, then the black, he told me. "After a while you get pretty good at making a straight line." Mr. Glaser said the bakery has made few changes to the original recipe, save eliminating shortening in a concession to the recent New York City ban on trans fats.

The Glaser's counterwoman plucked a cookie from the glass case and dropped it into a box wound with bakery twine. Though I carried it around all day, when I got home the two halves remained intact. I took my first bite, right down the center line. There was a slight resistance as my teeth met the surface. The sweetness of the icing melted into the floury plumpness of the yellow lemon-vanilla cookie, sticking to the back of my teeth. I imagined in another version, the icing might set into a crust that would crackle with each bite. The domelike shape made the cookie spongier in the center and firmer toward the edges. I found I could achieve a black-and-white melding only every three bites: I had to nibble down around the center bite to be able to reach it again. But when I did, I knew I was getting a taste of New York: stark contrasts coming together in a brash, frustrating, but ultimately satisfying way, and a mysterious past to make each bite just a little richer.