Bring a large pot of lightly salted water to a boil. Add ziti and cook for 8
to 10 minutes or until al dente; drain and rinse. In a medium bowl, mix ziti,
ricotta cheese, mozzarella cheese, egg and 1 1/2 cups spaghetti sauce. Preheat
oven to 375°F (190 degrees C). Lightly grease a 9x13 inch baking dish
and spoon in ziti mixture. Top with remaining spaghetti sauce, followed by
Parmesan cheese. Bake in preheated oven for 30 minutes; let stand for 15
minutes before serving.