Black and white cookie

A black-and-white cookie, half-and-half cookie, or half-moon cookie is a round cookie iced or frosted on one half with vanilla and on the other with chocolate. In the German language they are called Amerikaner. There are regional differences: a black-and-white cookie is flat, has fondant icing on a denser cake base, and is common in New York City, while a half-moon cookie is slightly dome-shaped, has frosting on a fluffier cake base, and is common in Central New York and Boston. Often one side is frosted higher than the other. Black-and-white cookies may also be found with frosting instead of fondant.
The origin of the black-and-white cookie in New York City is commonly traced to Glaser's Bake Shop, founded in 1902 by Bavarian immigrants in the Yorkville neighborhood of Manhattan. The black-and-white cookie was among the original recipes used by the bakery. Half-moon cookies, however, can be traced to Hemstrought's Bakery in Utica, New York, around 1925. The relationship between the two origins is murky; it is likely that both recipes share a common German root, although the origin and name of "Amerikaner" in Germany is also unclear. Purported explanations include a corruption of the word "Ammoniumhydrogencarbonat" (ammonium bicarbonate, a leavening agent), or that the cookie was (re)introduced to Germany by American GIs in the 1950s. German "Amerikaner" are often frosted entirely in white frosting. In the former East Germany, due to anti-American sentiment, the name "Ammonplätzchen" (Ammonia cookies) was used.
In popular culture.
Black-and-white cookies are mentioned twice on "Seinfeld", set in New York City. In the episode "The Dinner Party", Jerry eats a black-and-white cookie while waiting in a bakery with Elaine. He uses the cookie as a metaphor for racial harmony, saying the chocolate and vanilla represent black and white people living together and if they mix together well on a cookie they can do the same in society, suggesting the answer to poor race relations is to "Look to the cookie!"
Also in reference to racial harmony, Barack Obama dubbed them Unity Cookies when visiting a deli in Hollywood, Florida in 2008.