II
The Method
1
Prepare the spinach filling first so it is cold before assembly. Wilt the spinach in a dry pan, then press in batches — squeeze a handful firmly; if any liquid appears, press further. Chop finely and combine with the crumbled white cheese, nutmeg, and salt. Taste: the filling must be assertively seasoned. Spread on a tray and refrigerate until cold and dry.
2
Bring a large pot of well-salted water to a rolling boil. Prepare a bowl of cold water alongside. Lower one yufka sheet into the boiling water and hold for exactly 30 seconds — no less, or the layer will be stiff; no more, or it will tear on lifting. Remove with a wide skimmer and transfer immediately to the cold water to arrest cooking. Lift and lay flat on a clean cloth. Repeat for each sheet. This is where the dish lives or dies: the water-cooking produces the uniquely tender, pasta-like texture that defines su böreği; every second of boiling time matters.
3
Heat the oven and the baking dish — both must be hot before the börek is assembled. A cold start allows butter to pool in the bottom layer before the structure sets.
4
Brush the hot baking dish generously with clarified butter. Lay the first boiled yufka sheet flat in the dish and brush its entire surface with clarified butter — every centimetre; insufficient fat produces a solid block rather than distinct, separating layers. Lay a second sheet, brush again. Spread half the cold filling evenly across the surface.
5
Continue layering: a buttered yufka sheet, the remaining filling, then the final sheets, each brushed with butter. The top sheet receives a coat of beaten egg wash — this seals and colours the surface. Scatter sesame or nigella seeds evenly across the top.
6
Bake in the hot oven until the top is a deep, even amber and the surface is set firm — press the centre lightly with a finger; it should feel solid, not yielding. The underside, when the dish is tilted, should show colour rather than pale, butter-soaked dough.
7
Remove from the oven and leave to rest for 10 minutes before cutting. During this time the layers re-absorb the butter that has pooled during baking; cutting too soon releases it and collapses the structure. The börek is ready when a lifted portion holds its layers visibly distinct.