Preheat Oven to 190C/375F/Gas Mark 5. Trim spinach and wash it thoroughly. Put leaves in a large pan with no extra water but a little salt, and cook, covered, for 3-5 minutes, shaking pan occasionally, until leaves are soft. Drain Well. Brush a shallow 8-inch pie dish with melted butter and line with 6 sheets of pastry, brushing each sheet with melted butter. Ensure pastry edges overlap edges of dish. Heat oil in a pan and saute sliced onion until starting to soften. Stir in garlic and cumin, and cook for 1 minute. Mix turkey with plenty of seasoning, then add mozzarella cheese and ground nutmeg. Place half the spinach in base of dish. Cover with half the onion mixture, then spread with meat. add final layer of onions, then top with remaining spinach. Brush remaining sheets of filo pastry with butter. Cut into strips and arrange at random over top of pie. Sprinkle with sesame seeds, then bake in preheated oven for 30 minutes, or until golden brown and tender. Serve with prepared vegetables.