1/2 medium onion, chopped
1 tablespoon olive oil
2 garlic cloves, minced
1 pound lean ground beef
1 (26 oz) jar tomato & basil pasta sauce
3/4 tsp. salt, divided
1 (16 oz) box ziti pasta
3 tablespoons butter
3 tablespoons all-purpose flour
3 cups milk
1 cup grated Parmesan cheese
1/2 teaspoon pepper
2 cups shredded mozzarella cheese
Saute onion in hot oil in a large skillet over medium heat 5 minutes or until tender. Add garlic, and saute 1 minute. Add beef and cook, stirring until beef crumbles and is no longer pink. Drain beef mixture, and return to pan. Stir in pasta sauce and 1/2 teaspoon salt. Set aside.
Cook pasta according to package directions in large Dutch oven. Drain and return to Dutch oven.
Melt butter in a heavy saucepan over low heat; whisk in flour until smooth. Cook, whisking constantly, for 1 minue. Gradually whisk in milk; cook over medium heat, whisking constantly, until mixture is thickened and bubbly. Stir in Parmesan cheese, 1 cup of mozzarella cheese, the remaining salt, and the pepper. Pour sauce over pasta in Dutch oven, stirring until pasta is evenly coated.
Transfer pasta mixture to a lightly greased 13x9 inch baking dish. Top evenly with beef mixture; sprinkle evenly with remaining cup of mozzarella cheese.
Bake at 350 degrees for 20-25 minutes or until cheese is melted. Let stand 10 minutes before serving.