Preheat your oven to 180°C (350°F).
In a mixing bowl, combine the crumbled feta cheese with the beaten eggs and yogurt.
Lightly grease a baking dish with sunflower oil.
Lay one sheet of filo pastry in the dish, brush it with oil, then repeat the process with half of the remaining sheets.
Spread the cheese mixture evenly over the layered pastry sheets.
Cover the filling with the remaining filo sheets, brushing each with oil.
Bake in the preheated oven for 40 minutes, or until the top is golden brown.
Allow to cool slightly before cutting into squares and serving.