Wash and dry the spinach. Peel the onion and cut it finely. Chop the garlic cloves.
In a large saucepan, brown the onion with a little olive oil until it becomes translucent. Add the garlic, then the spinach. Sauté for 5-10 minutes, while the spinach begins to lose its volume.
Pour everything into a colander and squeeze the spinach to remove excess water. Let cool for a few minutes. Meanwhile, remove the leaves from the dill, mint and parsley sprigs. Chop them finely. Cut the feta into small cubes.
In a bowl, mix the spinach, dill, mint, parsley, feta. Grate the lemon zest on top and then add the juice of half the lemon. Add the eggs and mix well.
Then oil a large ovenproof dish with olive oil. Using a brush, lightly oil the filo leaves, then place 6 filo leaves at the bottom of the dish, distributing them so that about 5-6 centimeters of filo pastry overflows on each side of the dish.
Place the spinach filling on the filo leaves. And then cover with 6 other sheets of filo. Close the edges of the dish tightly. Finish by passing a thin layer of olive oil on top of the Spanakopita using a brush. Sprinkle with sesame seeds. Bake for 40 minutes at 180 ° C (conventional heat at the start, then fan oven for the last 10 minutes).
