Cook pasta according to package directions. Drain; place in a large bowl. In a small skillet, cook sausage over medium heat until no longer pink; drain and cut into 1/2-in. slices.
In a large saucepan, melt butter. Stir in the flour, 1 teaspoon salt and 1/4 teaspoon pepper until smooth; gradually add milk. Bring to a boil; cook and stir for 2 minutes or until thickened. Remove from the heat; stir in 1/4 cup Parmesan cheese. Pour over pasta; toss to coat.
In a small bowl, combine the egg, cottage cheese, parsley, and remaining Parmesan cheese, salt and pepper. Spoon half of the pasta mixture into a greased 2-1/2-qt. baking dish. Top with cottage cheese mixture. Add sausage to the remaining pasta mixture; spoon over the top. Sprinkle with mozzarella cheese and paprika.
Bake, uncovered, at 350° for 30-35 minutes or until a thermometer reads 160°. Yield: 6 servings.