This recipe is from the Greek town of Ioannina. It can be made ahead and served cold or can be assembled up to 8 hours in advance and kept in the refrigerator until 1 hour before serving time. When ready, bake and serve.
In a large bowl, combine the cheese, sugar, eggs and vanilla and beat with a mixer till creamy smooth.
Brush the bottom of a 10x14x2 inch baking pan or dish with the butter. Have ready the filo sheets, keeping them covered with plastic wrap to prevent them from drying out. Lay a filo sheet in the bottom of the pan and brush with butter. Repeat, brushing with butter, 5 more times.
Pour the filling mixture over the stacked and buttered filo sheets. Drizzle the filling with a little melted butter, then layer 5 more filo sheets on top, again brushing each sheet.
Cover the pan and refrigerate until the butter firms up. Can be pre-assembled up to this point.
Preheat the oven to 375 degrees F.
With a sharp knife, score the surface of the pastry through the top 5 sheets of filo dough into 10 diamonds or rectangles. Bake until golden brown, 35 to 40 minutes. Transfer pastry to a rack and let cool for 10 minutes. Cut along the score marks and finish allowing to cool until warm or to room temperature. Dust with powdered sugar and serve.