Wash spinach and discard stems. Dry thoroughly on absorbent paper and cut into pieces.
Sauté onion in butter until soft.
Add spinach and sauté a few minutes longer.
Cool. Add cream sauce, eggs, cheese and seasonings. Mix well.
Place 7 layers of phyllo pastry sheets in a 14 x 11 x 2-inch pan, brushing each sheet well with melted butter. Add spinach mixture, then place 8 phyllo pastry sheets on filling, again buttering each sheet.
Bake at 350 degrees F for about 30 minutes, or until crust is golden brown.