1. Wash spinach well and cut off any coarse stems. Chop coarsely and put into a large pan. Cover and place over heat for 7-8 minutes shaking pan now and then or turning spinach with a fork. Heat just long enough to wilt spinach so that juices can run out freely. Drain well in a colander, pressing occasionally with a spoon.
2. Gently fry onion in olive oil for 10 minutes, add chopped leek and spring onions and fry gently for further 5 minutes until transparent.
3. Place well-drained spinach in a mixing bowl and add oil and onion mixture, herbs and nutmeg. Blend thoroughly, adding salt and pepper to taste.
4. Place a sheet of fillo pastry on work surface and brush lightly with olive oil. Top with 3 more sheets of pastry, brushing each with oil.
5. Brush top layer lightly with oil and place half the spinach mixture along the length of the pastry towards one edge and leaving 4 cm (1 1/2 inches) clear on each side.
6. Fold bottom edge of pastry over filling, roll once, fold in sides then roll up. Place a hand at each end of roll and push it in gently like a concertina. Repeat with remaining pastry and filling.
7. Place rolls in an oiled baking dish leaving space between rolls. Brush tops lightly with oil and bake in a moderate oven for 30 minutes until golden. Serve hot cut in portions.