Preheat the oven to 375°F (190°C).
In a mixing bowl, combine the ground beef, breadcrumbs, grated Parmesan cheese, egg, minced garlic, oregano, salt, and pepper. Mix well until all ingredients are thoroughly combined.
Shape the mixture into meatballs, about 1 to 1.5 inches in diameter.
In a skillet over medium heat, cook the meatballs until browned on all sides, about 5-7 minutes. They don’t need to be fully cooked through at this point.
While the meatballs are cooking, boil the pasta according to package instructions until al dente. Drain and set aside.
In a large baking dish, mix the cooked pasta with marinara sauce. Gently add the meatballs to the dish, spreading them out evenly. Top with shredded mozzarella cheese.
Cover the baking dish with foil and bake in the preheated oven for 20 minutes.
Remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and golden.
Remove from the oven and let it cool for a few minutes. Garnish with fresh basil, if desired, before serving.