Bring a pan of salted water to boil and cook noodles in it till tender; drain.
Prepare spaghetti-sauce mix according to package directions, using the tomato paste and spinach puree.
Combine egg, cottage cheese, and salt; mix well.
In greased 10x6x1 1/2-inch baking dish, alternate layers of half each of the noodles, sauce, cottage cheese, Mozzarella, and Parmesan.
Bake in moderate oven (375°) 30 minutes.
Let stand 15 minutes before serving.