Preheat oven to 350°
Cook pasta according to package directions.
Drain, rinse and drain again.
Transfer to a warm bowl.
Separate the eggs.
In a small bowl, lightly beat the yolks. Set aside for white sauce.
Stir egg whites, feta cheese and 1/4 cup milk into the pasta. Set aside.
Prepare the red/meat sauce.
Cook the lamb and onion over medium high heat until meat is browned.
Drain off fat. Stir in the tomatoes, oregano, nutmeg, salt and pepper.
Bring to a boil, lower the heat and simmer, covered for 5 minutes.
Remove from heat, stir in 2/3 cup Parmesan cheese
Layer half of the pasta mixture in a lightly greased 8 x 8 x 2 baking dish.
Top with meat sauce and then with the remaining pasta mixture.
Prepare the white sauce.
In a medium saucepan, whisk together 1 1/2 cups milk, flour, salt and pepper.
Cook over moderate heat, whisking constantly for 8 minutes or until mixture is thickened and bubbly.
Slowly stir about 1 cup of the hot mixture into the lightly beaten egg yolks, then return this mixture to the saucepan.
Cook stirring constantly, for 3 minutes or until mixture thickens. (Do not boil)
Stir in the 1/4 cup Parmesan cheese. Pour the sauce over the pasta layer.
Bake for 30 to 35 minutes or until heated through.
Let stand 10 minutes before serving.