Combine eggs, milk, oil, water, and salt in a bowl. Place a sheet of thin dough and spread some of the mixture evenly on top of it. Say it two more times, so there are three layers in total. Combine feta cheese with cooked spinach and spread the mixture over the filo pastry. Moving from one side to the other to obtain a piece. Cut the food into triangles and place them on a baking sheet. Cover each triangle with egg yolk. Sprinkle with poppy seeds and bake at 180°C (356°F) for 15 minutes.
Have fun!