Spray 13 x 9 baking dish with cooking spray.
Cook ziti in saucepan as directed on package. Drain. cover to keep warm.
Meanwhile, in skillet, cook beef and onion; drain. Stir in pasta sauce and cinnamon. Bring to a boil. Reduce heat; simmer 10-12 minutes.
Heat oven to 350º
In same skillet, combine 1 cup of milk, flour, salt and pepper; mix with wire whisk until smooth. Stir in remaining 2 cups milk. Cook over medium heat until mixture boils and thickens. Remove from heat.
Beat eggs in bowl with wire whisk. Gradually add 1/2 of hot milk mixture, stirring constantly. Stir egg mixture into mixture in pan. Add cheese; mix well. Add cooked ziti; toss gently to coat evenly.
Place 1/2 of ziti mixture into pan. Spoon beef mixture evenly over ziti. Top with reamining ziti mixture. Cover tightly with sprayed floil.
Bake at 350º for 35-40 minutes or until bubbly.
Meanwhile, in small bowl, mix bread crumbs and butter.
Remove foil, sprinkle bread crumb mixture over top. Bake uncovered an additional 5 minutes.
Let stand 5 minutes before serving.