Cook macaroni as directed on package; drain.
Cook and stir beef and onion in 10-inch skillet until beef
is light brown; drain.
Spread half the macaroni in a greased 8-inch square baking
dish; cover with beef mixture.
Mix ½ cup of the cheese and cinnamon.
Sprinkle over beef mixture.
Cover with remaining macaroni.
Cook and stir milk and butter in 2-quart saucepan until
butter is melted.
Stir at least half the milk mixture gradually into
Blend into milk mixture in saucepan; pour over macaroni.
Sprinkle with remaining 1 cup cheese.
Bake uncovered at 325°F
until brown and center is set, about 50 minutes. Sprinkle
with nutmeg. Garnish with parsley if desired.