Bring a pot of lightly salted water to a boil and cook the fresh spinach for about 10 minutesuntil soft. Then drain in a sieve and squeeze well to remove all the excess water.
Now put the cooked spinach in a large bowl with grated parmesan, egg, ricotta and a pinch of salt. Mix everything thoroughly.
Prepare a 22cm/9in Ø springform pan and grease with butter. Roll out the puff pastry and place it in the springform pan. Form a rim of approx. 1cm/0.4in on the springform pan and press it down well. Prick the pastry several times with a fork. Cut off the excess puff pastry and keep for decoration.
Preheat the oven to 180°C/360°C top/bottom heat.
Now spread the spinach ricotta filling evenly over the dough and smooth it out with a dough scraper.
Then roll out the remaining puff pastry in a circle and cut out strips about 2cm/0.8in wide. With it then lay out a uniform diamond pattern on the filling.
Now put the cake in the oven and bake for 35 minutes until golden brown.
Allow to cool briefly before serving.Buon appetito!