Cook ziti according to package directions; drain and return to the pan.
Stir in Alfredo sauce and sour cream. Spoon half of this mixture into a lightly greased 3-qt. baking dish.
In a small bowl, combine the eggs, ricotta, 1/4 cup of the Parmesan cheese, the Romano cheese and parsley; spread over pasta. Top with remaining pasta mixture; sprinkle with mozzarella and remaining Parmesan.
Cover and bake in a preheated 350-degree oven for 25 minutes or until thermometer reads 160 degrees.
Uncover; bake 5-10 minutes more or untl bubbly. Serve immediately.