Chop the onions. Chop the fennel bulb. Wash and chop the spinach.
In a large heavy skillet, heat 2 tablespoons olive oil and saute the spinach lightly, just to wilt. Remove the spinach with a slotted spoon and drain in a colander. Heat 2 more tablespoons of olive oil and add the chopped onions and fennel. Cook, stirring with a wooden spoon, until wilted, about 7 minutes.
Place the spinach, fennel, and onions in a large bowl. Chop the dill and parsley, and add them to the bowl.
Lightly whisk the 2 eggs in a small bowl, then add them to the mixture, along with 2 more tablespoons of olive oil. Mix well.
Crumble the feta, and add it to the bowl, along with the salt, pepper, nutmeg, and optional cayenne (or raisins).
Preheat the oven to 350F. Lightly oil a pan. Use a 12" rectangular or oval pan. Lay a sheet of phyllo in the pan. The edges will hang over the edges. Brush this phyllo layer with olive oil. If you don’t have a pastry brush, just drizzle on the oil and rub it around with your (clean) fingertips. Repeat with 3-4 more sheets of phyllo, brushing each with olive oil.
Spread the filling evenly over the phyllo.
Pull up the outer edges of the phyllo layers, and wrap them around the filling, neatly. Top with 3-5 more layers of phyllo, each brushed with olive oil. To tuck the top layers down, gently tuck them into the edges of the pan using a metal spatula.
Bake for 50 minutes or more, until the phyllo is golden.