Preheat the oven to 375°F (190°C). Cook the spaghetti according to package instructions until al dente, then drain and set aside.

In a large bowl, combine the ground beef, breadcrumbs, Parmesan cheese, parsley, egg, minced garlic, salt, and black pepper. Mix until well combined.

Form the meat mixture into small meatballs, about 1 inch in diameter. Place the meatballs on a baking sheet lined with parchment paper.

Bake the meatballs in the preheated oven for 20 minutes, or until cooked through and browned.

In a large mixing bowl, combine the cooked spaghetti with the marinara sauce and Italian seasoning. Stir until the spaghetti is well coated.

In a 9x13 inch baking dish, spread half of the spaghetti mixture evenly on the bottom. Place the baked meatballs on top, then add the remaining spaghetti mixture.

Sprinkle the shredded mozzarella cheese evenly over the top.

Bake in the oven for an additional 15-20 minutes, or until the cheese is melted and bubbly.

Let cool for 5 minutes before serving.