Boil the spinach in a large pan of salted water for 2 minutes. Then place in ice-cold water and dry in a salad spinner. Now finely chop the spinach.
Mix 2 eggs, the ricotta and oregano in a bowl, season with sea salt and freshly ground pepper.
Lay out the puff pastry in a 5 cm high springform tin with a diameter of 20 cm and layer on top of each other. Leave a generous overlap around the edge. These flaps will later cover the torta. Keep 1 extra sheet of pastry for the lid. Brush a little oil between the layers.
Fill the cake tin with half of the spinach, then pour the ricotta mixture on top. Press 4 wells into the filling and slide a raw egg into each one. Be careful not to damage the egg yolks. Carefully layer the remaining spinach on top, then use the remaining pastry sheet to fold the pastry into a lid and seal the torta.
Whisk the last egg and brush the cake. Bake for one hour or until golden brown.