The word baklava is first attested in English in 1650, borrowing from Ottoman Turkish and is used in many languages. The earliest reference to baklava is in a poem by 15th century mystic Kaygusuz.
Although the history of baklava is not well documented, its current form was probably developed in the imperial kitchens of the Topkapı Palace in Constantinople (modern Istanbul). The Sultan presented trays of baklava to the Janissaries every 15th of the month of Ramadan in a ceremonial procession called the Baklava Alayı.
In the Byzantine Empire, the traditional placenta cake (known as "koptoplakous",) a dish similar to baklava, was consumed. The earliest known recipe, from the 2nd century BC, is a honey-covered baked layered-dough dessert.
The Greeks and the Turks still argue over which dishes were originally Greek and which Turkish. Baklava, for example, is claimed by both countries. Greek and Turkish cuisine both built upon the cookery of the Byzantine Empire, which was a continuation of the cooking of the Roman Empire. Roman cuisine had borrowed a great deal from the ancient Greeks, but placenta (and hence baklava) had a Latin, not a Greek, origin.
Anti-Greek Cato left this recipe: "Shape the placenta as follows: place a single row of tracta along the whole length of the base dough. This is then covered with the mixture [cheese and honey] from the mortar. Place another row of tracta on top and go on doing so until all the cheese and honey have been used up. Finish with a layer of tracta. ... place the placenta in the oven and put a preheated lid on top of it ... When ready, honey is poured over the placenta." — Cato the Elder, De Agri Cultura 160 BC
The word "placenta" originally comes from the Greek language plakous (πλακοῦς), which means something "flat and broad". Although there are no surviving recipes for Greek plakous, the term is known from the work of comic poet Antiphanes.
According to a number of scholars, koptoplakous was a precursor to the modern baklava. Historian Speros Vryonis describes koptoplakous as a "Byzantine favorite" and "the same as the Turkish baklava", as do other writers. The name is used today on the island of Lesbos for thin layered pastry leaves with crushed nuts, baked, and covered in syrup.
There are many regional variations of baklava. In Greece, walnuts are more common than pistachios, and the dessert is often flavored with cinnamon. In Iran, fragrant cardamom is added to a sweetened walnut filling. In Azerbaijani cuisine, it is made with walnuts or almonds, is usually cut in a rhombus shape and is traditionally served during the spring holiday of Nowruz. In Gaziantep, locally grown pistachios are used, and the dessert is often served with kaymak cream.
Baklava is normally prepared in large pans. Many layers of filo dough, separated with melted butter and vegetable oil, 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 filo. Most recipes have multiple layers of filo and nuts, though some have only top and bottom pastry.