Passover Spanekopita

When it comes to adapting the recipes of their adopted homelands to their time-honored religious beliefs, Jews have been dazzlingly ingenious. Consider this Passover version of Greek spanekopita (spinach pie). Traditional spanekopita, of course, would be made with filo dough. Greek Jews achieved something of the buttery crispness of the pastry by sandwiching the filling between buttered or oiled sheets of matzo. I like the sourish tang provided by grated feta cheese, but you could also use