"A Comedy of Betrothal" written by Leone de' Sommi Portaleone, 1525–1590
The first written reference to these cookies come from a 16th century comedy play written by an Jewish-Italian playwright. The play satirized the religious leaders' habits of looking for biblical references to explain new traditions.
One of the jokes in the play is based on Haman being a homonym of the Hebrew word for the manna that the people of Israel ate in their 40-year desert sojourn. One of the characters in the play makes the ridiculous assertion that the commandment to eat "ozney haman" in Purim comes from the passage in Exodus that says that the children of Israel ate the manna. Another character responds with an interpretation that it must mean that Jews are commanded to eat oznei Haman.1
(This is meant to be funny)
"Haman's Ears, Ozne Haman," Medieval Europe
Why do we eat “Haman’s ears” on Purim? We eat them to remember the execution of Haman, since before he was executed his ears were cut off.
However, no such ear cropping is mentioned in the Book of Esther!!! That was however a custom in Medieval Europe, where a condemned man's ears might be cut off before execution2.
However, “oznayim” can sometimes refer to non-Purim pastries. In fact, in describing the manna which fell from heaven while the Jews were in the desert, both Rabbi Yosef ibn Kaspi (1279-1340)3 and Rabbi Don Yitzchak Abarbanel (1437-1508)4 describe a pastry called oznayim, with no mention of Haman or Purim at all.
Mohntaschen, 16th century Germany
In Yiddush, Mohn means “poppy seed” and Tasch means “pocket." The mohntaschen date back at least to 16th-century Germany, when mohn, or poppy seeds, were eaten as a snack during winter, when little grew. The seeds, from the flower that produces the powerful drug opium, were also turned into jam and encased in pastries for special occasions.5
Haman's hat
In time, the American-English interpretation arose that the three cornered cakes are eaten because Haman wore a three cornered hat when he became prime minister to Ahasuerus.6 It certainly isn’t very traditional to Persian culture: tricornes, or three-cornered hats, having come into temporary vogue only in the late 18th century, just in time to be worn by George Washington....7
This has been picked up by Jews speaking others languages too, such as Spanish, in which hamantaschen are now sometimes called sombreros de Aman.
Ears, Hat, whatever. Why do we EAT it?
R. Yaakov Kamenetsky offers yet another reason for eating hamentashen on Purim. As we eat the hamentashen and eating is a form of destroying the item being eaten. Therefore, in eating hamentashen, we are fulfilling the commandment (figuratively) of destroying Haman (also why we make noise after we hear Haman's name).8
Other Purim foods
Amongst Sephardic Jews, deep-fried strips of dough called “Orejas de Haman” (Haman’s ears) are often the primary Purim treats, while with some Western European and Scandinavian Jews, it is traditional to bake and eat gingerbread men in the shape of Haman. As we can see, despite the differences in the anatomical details, there is definitely a pattern of “eat and erase the villain” behavior in Purim foods around the world!
Another typical feature of Purim foods is the idea of having a hidden filling, a reference to the notion that there are many secrets and surprises in the story of Purim. In Ashkenazi culinary tradition, it is customary to eat Kreplach (a meat or potato filled dumpling), pierogi, stuffed cabbage, or knishes. Italian Jews often celebrate Purim with spinach-filled pasta and “buricche,” puff pastry turnovers filled with vegetables or meat; while Persian and Iraqi Jews eat “sambusak,” turnovers filled with savory ingredients such as ground lamb, cheese, chickpeas, chicken or spinach.
Because Esther supposedly kept to a strict vegetarian diet while in Haman’s palace, Jewish communities around the world eat foods containing nuts and seeds at Purim. Many Iraqi Jews eat “Hadgi Badah,” sugar cookies with cardamom and almonds. Another Middle Eastern Purim favorite, especially in Lebanon and Syria, are mamoul, semolina cookies filled with nuts or dates.9
1C. Shirman, Letoldot Hashira v’Hadrama Haivrit, 2, pg. 52-53, cited by R’ Eliezer Brodt in “The Origins of Hamentashen in Jewish Literature: A Historical-Culinary Survey Revisited.”
3Metzarif Lekesef on Exodus 16:31
4See commentary of the Abarbanel on Exodus, ch. 16 (p. 143 in standard edition).
5Thinking outside the Triangle
6Hayyim Schauss, The Jewish Festivals (Random House, 1938; Hebrew, 1933), p. 270.
8Yaakov Michoel Jacobs, Bemechitzas Rabbeinu: Hagaon Rav Yaakov Kamenetzky, zt"l (Feldheim, 2005), p. 142