- Mix ground beef, breadcrumbs, Parmesan, egg, garlic, Italian seasoning, salt, and pepper in a bowl. Form into 1–2 inch balls. Sear in a skillet with olive oil over medium heat until browned on all sides, about 8 minutes. 
- Boil spaghetti in salted water until just shy of al dente. Drain and toss with a bit of olive oil to keep from sticking. 
- Preheat oven to 375°F (190°C). Spread 1 cup marinara on the bottom of a 9x13-inch dish. Add half the pasta, top with meatballs, then the rest of the sauce. Sprinkle with garlic powder, Italian seasoning, mozzarella, and Parmesan. 
- Cover with foil and bake for 15 minutes. Uncover and bake 10–15 minutes more, until cheese is golden and bubbly. 
- Let rest for 5 minutes. Garnish with fresh basil or parsley before serving.