Bring a large pot of water to a boil and add plenty of salt. Boil the pasta for 3 minutes less than the package directs.
In a large sauce pan brown the ground beef. Drain the fat. Stir in the spaghetti sauce.
In a small pot melt the butter and whisk in the flour. Cook until hot and bubbly. Whisk in the milk and cream and cook 5 minutes or until the sauce has thickened to a gravy consistency. Stir in the pepper and nutmeg.
In a medium bowl mix together the ricotta, egg, 1 teaspoon of Italian seasoning, and the Parmesan cheese.
Spread 1/4 cup of the meat sauce in the bottom of a 9x13 baking dish.
Pour in half of the ziti and spread it out. Pour on half of the meat sauce and spread it over the ziti. Pour on half of the bechamel sauce.
Drop dollops of the ricotta mixture over the meat sauce and then sprinkle with half of the mozzarella.
Repeat the layers of ziti and meat sauce. Pour the remaining bechamel evenly over the top. Place the remaining cheese on top and sprinkle with the 1/2 teaspoon of Italian seasoning.
Bake covered for 30 minutes in a preheated 350 degree oven.
Remove the cover and bake for another 10-15 minutes or until the cheese is melted and bubbly.