Store for up to four days and reheat in the oven until crisp to serve. 

• Thaw puff pastry according to package directions — if frozen, or bring to room temperature if chilled. Heat oven to 200°C. Line two baking sheets with baking parchment.
• Bring a large saucepan of water to boil and add some salt.  Add the spinach leaves and cook for 30 seconds. Drain. Once the spinach cools, squeeze out as much water as possible.
• To prepare the filling, place the spinach on a cutting board and chop roughly.  Place into a medium bowl.  Add the chopped onion, lemon juice, oil, za’atar and mix well with a fork. Add the cream cheese and mash into the spinach as best as possible.  Add salt and black pepper to taste.
• When the pastry is thawed, sprinkle a little flour on the parchment and unroll the pastry on top. Use a rolling pin to roll the pastry to smooth out the creases. Every few rolls, lift up the dough and sprinkle a little flour underneath.
• Use a 7cm drinking glass or round cutter to cut the dough into circles. Use a metal flat blade spatula to lift the circle and place on another spot on the parchment.  Brush the circle with the beaten egg. Place a generous teaspoon of filling in the centre and then fold in the three sides towards the middle to form a triangle, leaving a small opening in the center. Pinch the three sides together very tightly. Place on the prepared baking sheets.
• When all of the pastries are shaped, pinch the corners tightly a second time. Brush pastries with the remaining beaten egg and sprinkle the sesame seeds on top and on the sides.
• Bake for 25 minutes or until golden.