Feta and kale börek

Heat the oil in a frying pan over a medium heat and fry the onion for 10 minutes until very soft. Meanwhile, cook the kale in a pan of boiling salted water for 1 minute until wilted. Drain well and leave to cool a little in the colander, then transfer to a clean tea towel and wring out as much water as possible.

Put the kale, feta and onion in a large bowl and mix with lots of black pepper and a little salt. Heat the oven to 180C/fan 160C/gas 4.

Generously butter a 23cm round cake tin or pie dish (a springform cake tin works well) with some of the melted butter. Unravel the filo sheets one at a time on a large, clean worksurface, keeping the rest under a damp tea towel to prevent them drying out. Brush all over with some of the melted butter and, working fairly quickly, arrange a second filo sheet at one end of the first, overlapping by about 10cm. Brush the second sheet with butter, then repeat the process so you have three sheets of connected filo. Layer the remaining three sheets of filo over the top, brushing with butter as before, so you have a double layer of filo.

With the longest side facing you, spoon the filling over the filo rectangle in a long, thin line about 2cm from the edge of the pastry. Lift the pastry edge up over the filling to enclose and roll up into a tight sausage shape. Brush all over with more melted butter, then spiral the sausage into a coil and transfer to the prepared tin, using a fish slice to help you, if needed. Brush with the beaten egg and bake for 35-45 minutes or until golden and crisp. Cut into slices and serve hot or at room temperature.