The word baklava is first attested in English in 1650, a borrowing from Ottoman Turkishباقلوا/bɑːklɑvɑː/. The name baklava is used in many languages with minor phonetic and spelling variations.
The origin of the name is unknown. Buell argues that the word "baklava" may come from the Mongolian root baγla- 'to tie, wrap up, pile up' composed with the Turkic verbal ending -v; baγla- itself in Mongolian is a Turkic loanword.
Though the suffix -vā might suggest a Persian origin, the baqla- part does not appear to be Persian. Another form of the word is also recorded in Persian, باقلبا (bāqlabā).
Although the history of baklava is not well documented, there is evidence that its current form was developed in the imperial kitchens of the Topkapı Palace in Istanbul based on a Central AsianTurkic tradition of layered breads.
The tradition of layered breads by Turkic peoples in Central Asia suggests the "missing link" between the Central Asian folded or layered breads (which did not include nuts) and modern phyllo-based pastries like baklava would be the Azerbaijani dish Bakı pakhlavası, which involves layers of dough and nuts. The Uzbekpakhlava, puskal or yupka, and Tataryoka, sweet and salty savories (boreks) prepared with 10–12 layers of dough, are other early examples of layered dough style in Turkic regions. The thin phyllo dough used today was probably developed in the kitchens of the Topkapı Palace.
The Sultan presented trays of baklava to the Janissaries every 15th of the month of Ramadan in a ceremonial procession called the Baklava Alayı.
One of the oldest known recipes for a sort of proto-baklava is Güllaç, also found in Turkish cuisine. It consists of layers of phyllo dough that are put one by one in warmed up milk with sugar. It is served with walnut and fresh pomegranate and generally eaten during Ramadan. The first known documentation of güllaç is in a food and health manual written in 1330 that documented primarily Mongol-Turkic foods called Yinshan Zhenyao (飮膳正要), which was written by Husihui (忽思慧) who was a Turkic physician to the Mongol court of the Yuan dynasty
Other theories about baklava's origins include:
That it dates back to ancient Mesopotamia, and was mentioned in a Mesopotamian cookbook on walnut dishes. But there is no evidence for this.
That it was a popular Byzantine dessert. Many Ottoman sweets are similar to Byzantine sweets, using dough, sesame, wheat, nuts and fruits, and some were similar to the Ottoman börek, halva, and so on.  There are some similarities between baklava and the Ancient Greekgastris (γάστρις),kopte sesamis (κοπτὴ σησαμίς), kopton (κοπτόν), or koptoplakous (κοπτοπλακοῦς).Gastris is mentioned in the Deipnosophistae and Speros Vryonis called it a "Byzantine favorite". But though gastris contained a filling of nuts and honey, its outer layers did not include any dough, but rather a honey and ground sesame mixture similar to modern pasteli or halva. Even so, there is strong possibility that such similarities are simply due to the natural foods of the common geography that the two empires successively ruled.
Baklava is normally prepared in large pans. Many layers of phyllo dough, separated with melted butter, are laid in the pan. A layer of chopped nuts—typically walnuts or pistachios, but hazelnuts are also sometimes used—is placed on top, then more layers of phyllo. Most recipes have multiple layers of phyllo and nuts, though some have only top and bottom pastry.
Before baking, the dough is cut into regular pieces, often parallelograms (lozenge-shaped), triangles, or rectangles. A syrup, which may include honey, rosewater, or orange flower water is poured over the cooked baklava and allowed to soak in.
Baklava is usually served at room temperature, often garnished with ground nuts.
In Georgia, baklava is made with honey, sugar, walnuts, vanilla, butter, and sour cream.
In Iran, a drier version of baklava is cooked and presented in smaller diamond-shaped cuts flavored with rose water. The cities of Yazd and Qazvin are famous for their baklava, which is widely distributed in Iran. Persian baklava uses a combination of chopped almonds and pistachios spiced with cardamom and a rose water-scented syrup and is lighter than Middle Eastern versions.
In Israel, baklava is made of phyllo pastry sheets, nuts, such as pistachios, walnuts, hazelnuts, and almonds, sweet butter, clove, sugar, cinammon, and the syrup combined with orange and lemon rind.
In Jordan, baklava is made of dough layers filled with nuts, such as pistachios, and sugar or honey syrup.
In Lebanon, baklava is made of filo pastry filled with nuts and steeped in Attar syrup (orange or rose water or sugar) or honey. It is usually cut into triangular or diamond shapes.
In Syria, baklava is prepared from phyllo dough sheets, butter, walnuts and sugar syrup. It is cut into lozenge pieces. Baklava from Aleppo is made with the local pistachios and samna from Hama.
^Speros Vryonis The Decline of Medieval Hellenism in Asia Minor, 1971, p. 482
^Charles Perry, "The Taste for Layered Bread among the Nomadic Turks and the Central Asian Origins of Baklava", in A Taste of Thyme: Culinary Cultures of the Middle East (ed. Sami Zubaida, Richard Tapper), 1994. ISBN 1-86064-603-4.
Perry, Charles. "The Taste for Layered Bread among the Nomadic Turks and the Central Asian Origins of Baklava", in A Taste of Thyme: Culinary Cultures of the Middle East (ed. Sami Zubaida, Richard Tapper), 1994. ISBN 1-86064-603-4.