Cook manicotti according to package directions. Meanwhile, melt butter in a saucepan. Stir in the flour until smooth; gradually add milk. Bring to a boil; cook and stir for 2 minutes or until thickened. Stir in Parmesan cheese until melted; set aside. Drain manicotti; set aside. In a large skillet, cook sausage over medium heat until no longer pink; drain. Add the chicken, spinach, eggs, mozzarella cheese and 3/4 cup white sauce. Stuff into manicotti shells. Spread 1/2 cup spaghetti sauce in each of two ungreased 13-inch by 9-inch baking dishes. Top with manicotti. Pour remaining spaghetti sauce over the top. Reheat the remaining white sauce, stirring constantly. Pour over spaghetti sauce. Bake, uncovered, at 350° for 45-50 minutes or until a thermometer inserted in the filling reads 160°. Sprinkle with parsley.