Börek

300g of cavolo nero, (weight with stalks, which yielded 150g without stalks)

8 sheets of yufka pastry, or filo pastry

200g of feta, or Sütdiyarı Picnic Börek Cheese if you can find it (or another white Turkish cheese)

100g of butter, melted

1 egg, and 1 egg yolk, beaten lightly with a fork