In a skillet, cook and crumble the ground beef with garlic powder, onion, powder, salt, & pepper. Remove from pan and drain.
In the same pan, melt the butter, and mix with the flour until it forms a paste.
Add the milk gradually, and bring to a boil, until it thickens into a creamy sauce. Set aside.
In a bowl, mix the rigatoni with the eggs. Divide between two 9x13 inch (23x33 centimeter) baking dishes.
Layer on the marinara, ground beef, mozzarella, white sauce, and parmesan.
Bake both for 30-35 minutes, or until cheese is melted and golden brown.
Cool and freeze extra casserole up to 2 months. (To cook, transfer to the refrigerator overnight. Bake covered at 375°F (190°C) for 40 minutes. Remove cover and bake an additional 10 minutes.)