1Heat oven to 350°F. Spray 13x9-inch (3-quart) glass baking dish with cooking spray. Cook and drain pasta as directed on package, using minimum cook time.
2Meanwhile, in 10-inch skillet, heat oil over medium-high heat. Cook beef and onion in oil 5 to 7 minutes, stirring occasionally, until beef is thoroughly cooked and onion is tender; drain. Stir in tomatoes, salt and cinnamon. Cook 3 minutes longer or until thoroughly heated.
3In 2-quart saucepan, melt butter over medium-low heat. Stir in flour. Cook and stir until smooth and bubbly. Increase heat to medium-high. Gradually add milk, stirring constantly until mixture boils and thickens. Remove from heat; stir in nutmeg and 1/2 cup of the cheese until melted. Slowly stir in beaten eggs with wire whisk until blended. Arrange pasta lengthwise in baking dish. Top with beef mixture and sauce. Sprinkle with remaining 3/4 cup cheese. Bake uncovered 40 to 45 minutes or until bubbly and golden brown.