- Mix together the spinach, Feta, dill, parsley, leeks, eggs, salt and pepper. Brush the bottom of an 8x8 inch baking pan with olive oil. Place a sheet of Fillo dough in the pan, brush lightly with olive oil. Use kitchen scissors to trim the Fillo to fit. Repeat until you have 6 layers, lightly brushing each layers with olive oil. Place spinach and greens mixture on top of the 6 layers of Fillo dough, in an even layer. Flatten with a spatula. To create a "top" for your spinach pie, layer another six pieces of Fillo dough on top of the spinach mixture, brushing each later with olive oil as you go. Bake for 30-50 minutes at 350 degrees F, until golden brown.