Mix the feta in a bowl with baby spinach, chillies, spring onions and dill. Season with salt and pepper.
Brush the base of a large frying pan with extra virgin olive oil. Mix the rest of the oil with the milk.
Lay two large sheets of the filo pastry over the pan so that it drapes over the sides. Spoon half the filling. Rip another piece of folo pastry in halfand tear it into large pieces, dip them into the milky olive oil, mix and them roughly on top of the filling in the pan.
Spoon the rest of the filling onto the middle layer. Dip the rest of the filo pastry in the milky oil and lay it on top in the same way to make the top layer.
Fold the filo hanging over the sides back over the top and brush again with the milky oil. Fry for three to four minutes each side on a medium heat. Cut into wedges and serve with the yogurt if you wish.