Pound chicken to about a ½-inch thickness. Dip into egg, then into bread crumbs. Saute chicken in olive oil until browned and cooked through (about 5 minutes per side). Season with salt and pepper. Meanwhile, steam spinach and drain well. Arrange chicken cutlets in baking pan and top each with spaghetti sauce. Add a layer of spinach over the sauce, then a slice of cheese. Bake at 350 degrees F for about 10 minutes, to melt cheese.