Preheat your oven to 375°F (190°C).
Cook the spaghetti according to package instructions; drain and let cool slightly.
In a large bowl, mix the spaghetti, eggs, and Parmesan cheese until well combined.
Press the spaghetti mixture into the bottom and up the sides of a greased pie dish to form a crust.
In a skillet, sauté the chopped onion and garlic until fragrant.
Add the ground beef, Italian seasoning, salt, and pepper; cook until browned.
Stir in 1 cup of marinara sauce into the meat mixture.
Pour the meat sauce into the spaghetti crust, spreading it evenly.
Top with the remaining marinara sauce and sprinkle mozzarella cheese on top.
Bake in the preheated oven for 25-30 minutes, or until the cheese is bubbly and golden.