1. Over a low heat sauté the leeks, spring onions and garlic with 2 tbsp of the olive oil.
2. Transfer to a bowl.
3. Sauté the spinach in 2 tbsp of the olive oil  until wilted. Transfer to the bowl with the leeks.
4. Let it cool and add the eggs, cheeses, dill and lemon zest. Mix carefully and season well with salt and freshly ground pepper.
5. Lightly brush a 26 * 28 cm circular pan  with olive oil and lay 5 thin sheets of filo pastry, well brushed with olive oil.
6. Spoon in the filling, then fold over the hanging filo sheets.
7. Crinkle the last three filo sheets and lay on top of the filling.
8. Brush with olive oil and sprinkle with black sesame seeds.
9. Bake for 35’ – 40’ in a preheated oven 180° C (350 F), placing the pan on the middle rack, until crisp and golden.

Tip: Place the pan on the bottom rack 15’ before the end, to dry well at the base from the filling liquids.