Pre-heat an oven to 200C/180C for fan/ gas mark 6.
In a large pan, heat the olive oil over medium heat and gently fry the onion until soft and translucent. Set aside to cool.
In a large bowl, combine the cooled cooked onions with the herbs and feta cheese.
Squeeze the spinach through a clean kitchen towel or muslin cloth until the excess water is completely drained. Once dry, combine with the onions, herbs, and feta. Season with salt, pepper, and nutmeg to taste. Mix in the beaten eggs. To layer the pie, start by brushing the bottom of a round baking dish with melted butter. Lay the filo pastry along the bottom and allow the edges to hang over the side of the dish. Repeat the process by laying filo sheets in alternate directions for 4-5 sheets. Brush each sheet with a little melted butter.
Add the filling to the centre of the pie, and top with another 2-3 sheets of filo pastry and melted butter. Fold over the overhanging sheets, and finish with melted butter.
Bake in the centre of the preheated oven for 35-40 minutes until the pie is crisp and golden. Serve, cut into triangular wedges.
