A cookie (which I personally find delicious) which is generally in the shape of a circle about 6 inches (15 cm) in diameter. It is made with a simple sugar cookie base, and then topped half with thick vanilla and chocolate frosting, divided by a diameter of the circle. On a good Black & White, the frosting will be slightly shiny due to the addition of a small amount of oil to the frosting mix. The thin layer is slightly hardened, giving it a nice texture without melting immediately or chipping one's teeth.
The black & white cookie is often seen at bakeries and delis in New York, and Jerry Seinfeld once used it as a metaphor for racial harmony on an episode of Seinfeld. The black and the white come together in one perfect circle, totally unified. However, when Seinfeld gets an upset stomach and vomits after eating the cookie, he blames racial inequality for the illness.