Add cream cheese, Feta, eggs, salt and pepper; mix well.
Place 10 layers of phyllo pastry sheets in a 12 x 16 x 2-inch pan, brushing each sheet well with melted butter. Add spinach mixture, then place another 10 layers of phyllo, buttering each sheet.
Bake at 350° for 30 minutes.
Cut into squares before serving.
You can brush the spanakopeta with a slightly beaten egg before baking for a nice luster.