A great pasta and ground beef casserole. Hearty and delicious. The beauty of this recipe (besides great taste) is it's ability to freeze (and defrost) so well, with no loss of flavour, making it ideal for OAMC (once a month cooking).
For the meat sauce, put some olive oil in a large pot; saute onion until lightly browned; add garlic; add meat and cook until brown, crumbling with a fork; add remaining meat sauce ingredients to skillet; mix well; cover and simmer for 1 hour, stirring occasionally, until quite thick; let mixture cool; remove and discard cinnamon stick and bay leaf.
Prepare pasta by boiling until al dente in plenty of boiling, salted water; drain and place pasta in a large bowl; add butter, milk, eggs and 1/2 cup cheese; gently stir to coat; set aside.
To prepare bechamel sauce, melt butter over medium heat in a saucepan; stir in flour until smooth, cook, whisking for 2 minutes; gradually add milk, stirring, until thickened; lower heat; add salt, pepper and nutmeg; remove from heat.
In medium-sized bowl, beat 3 eggs; slowly add hot cream sauce to eggs; stir thoroughly so eggs don't curdle.
Preheat oven to 350°F and butter or oil (with olive oil) a large baking pan (my pan is about 18" x 10").
Empty 1/2 of the penne mixture over bottom of pan; cover evenly with all of meat sauce; sprinkle 1/3 of the cheese over meat sauce; add remaining penne mixture, spreading evenly; sprinkle another 1/3 of the cheese over top; pour bechamel sauce evenly over entire casserole; top with remaining cheese.
Bake until bechamel sauce sets and has golden-brown patches across top, approximately 45 minutes to 1 hour; cool at least 20 minutes before cutting into pieces for serving.
Freezer Notes: Once the baked pastitsio has completely cooked, cut serving-size pieces, double-wrap in foil and freeze. Defrost in the usual manner and reheat in microwave (or oven) for a delicious, quick meal, when there's little time to cook and dinner is ready and waiting in the freezer!