Boil the macaroni in salted water and drain them well. Mix them with 1/2 the grated cheese and the egg whites.
Pour 1/2 the macaroni mixture in an oiled tray. Sprinkle a little oil. Braise oil with chopped onions, add the mince and once it breaks down into bits, pour in the tomatoes as well. Season with the spices.
Distribute the mince and tomatoes over the macaroni, sprinkle grated cheese and cover with the remaining 1/2 of macaroni.
Prepare a Bechamel sauce from the ingredients listed and pour it on top. Bake the whole thing in a preheated 356°F (180 °C) oven about 40 min. Take the Pastitsio out, grate more cheese on top, return to the oven for it to crisp for 10 min. It's really tasty!