Lightly salt sliced eggplant and set aside. In a bowl, mix spinach, ricotta, feta, egg and spices. Spray an 8x8 (preferable glass) pan with non-stick spray. Rinse eggplant and pat dry. Lay 3 or 4 slices of eggplant in the bottom of the pan (whatever fits). Put about 1 cup of spinach mixture on top and spread out to cover eggplant. Repeat layers, ending with spinach until eggplant and spinach are used up (I think about 3 layers total does it). Pour tomato sauce over top, and let it run down sides.

Sprinkle with parmesan if using it, and bake at 375 for 30-40 minutes, until a knife cuts through easily, indicating that the eggplant is cooked. Let rest about 5 minutes before serving. 4 large or 6 small servings.