Prepare the Pasta:
Cook the pasta according to package instructions until al dente. Drain and return to the pot.
Stir in the beaten eggs and Parmesan cheese. Set aside.
Make the Meat Sauce:
Heat the olive oil in a large skillet over medium heat.
Sauté the onion and garlic until translucent.
Add the ground meat and cook until browned.
Stir in the crushed tomatoes, cinnamon, salt, and pepper.
Simmer for about 15 minutes, then remove from heat.
Prepare the Béchamel Sauce:
Melt the butter in a saucepan over medium heat.
Whisk in the flour and cook for a minute.
Gradually add the milk, whisking continuously to prevent lumps.
Season with nutmeg, salt, and pepper.
Cook until the sauce thickens. Remove from heat and let it cool slightly.
Stir in the beaten eggs.
Assemble the Pastichio:
Preheat the oven to 350°F (175°C).
Lightly oil a large baking dish.
Spread half of the pasta in the dish.
Cover with the meat sauce.
Add the remaining pasta.
Pour the béchamel sauce over the top, spreading evenly.
Bake:
Bake in the preheated oven for about 45 minutes, or until the top is golden and the sauce is bubbly.
Let the pastichio rest for 15-20 minutes before serving.