Cook ziti; drain and set aside. Cook sausage in oil until browned; drain well. Slice diagonally and then set aside. Melt butter over low heat; add flour and stir til smooth. Cook for 1 minute, stirring constantly. Gradually add milk; cook over medium heat, stirring constantly, til mixture is thick and bubbly. Stir in 1/4 cup Parmesan, 1 tsp salt and 1/2 tsp pepper. Add pasta; stir well and set aside. Combine rest of parmesan, cottage cheese, egg, parsley, salt and pepper. Place half of ziti mix in greased 13x9 pan; top with cottage cheese mix and half of sausage. Top with rest of ziti and sausage. Sprinkle with mozzarella. Cover and bake at 350F for 1 hour.