Creating Pastitsio can be an enjoyable experience if you follow these straightforward steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Cook Pasta: Boil a large pot of salted water. Add the penne pasta and cook according to the package instructions until al dente. Drain and set aside.
3. Prepare the Meat Sauce: In a large skillet, heat olive oil over medium heat. Add the chopped onion and minced garlic, sautéing until soft.
4. Add Ground Meat: Incorporate the ground beef or lamb and cook until browned. Drain any excess fat.
5. Simmer Sauce: Stir in crushed tomatoes, tomato paste, cinnamon, allspice, salt, and pepper, letting it simmer for about 15 minutes until thickened.
6. Make the Béchamel Sauce: In a saucepan, melt the butter over medium heat. Whisk in the flour and cook for 2 minutes. Gradually add milk, whisking constantly until thickened. Remove from heat.
7. Combine Béchamel: Stir in ½ cup grated Parmesan cheese, nutmeg, and eggs into the béchamel sauce until smooth.
8. Layer the Dish: In a large baking dish, layer half of the cooked pasta on the bottom. Spread the meat sauce evenly over the pasta, followed by the remaining pasta on top.
9. Top with Béchamel: Pour the béchamel sauce over the layered pasta and meat mixture, spreading it evenly.
10. Sprinkle Cheese: Finish by sprinkling the remaining ¼ cup of grated Parmesan cheese on top.
11. Bake: Place the dish into the oven and bake for 45 minutes until the top is golden and bubbly.
12. Cool: Let it cool for about 15 minutes before slicing.

By following these simple steps, you’ll be well on your way to creating an incredible Pastitsio that embodies the true spirit of Greek cooking!