Heat oil in large pot over low heat. Cook onion for 1-2 minutes. Add spinach and cook for another 1-2 minutes. Remove from heat.
In small bowl, beat eggs and season with salt and pepper. Stir in feta, green onion, oregano and nutmeg.
Preheat oven to 350. Lay 1 sheet of pastry into dry pie dish and brush with melted butter. Repeat with another 3 sheets.
Keep phyllo covered with a damp towel while working. Mix egg mixture into pot of spinach. Spoon into pie dish.
Cover with 4 sheets of pastry, brushing with butter between each layer. Press edges together.
Scrunch up last 2 sheets on top and brush with butter. Bake 35-40 minutes or until top is golden brown.
Let cool 10 minutes before cutting.