In a large bowl, combine ground turkey, breadcrumbs, Parmesan cheese, egg, minced garlic, chopped onion, parsley, oregano, salt, and black pepper. Mix until all ingredients are evenly incorporated.
Form the mixture into 16 evenly sized meatballs, about 1 1/2 inches in diameter.
Heat olive oil in a large skillet over medium heat. Add the meatballs and cook for 5-7 minutes, turning occasionally, until browned on all sides but not fully cooked through.
Pour marinara sauce into the skillet with the meatballs. Reduce heat to low, cover, and simmer for 15 minutes, or until meatballs are cooked through and sauce is heated.
While the meatballs are simmering, bring a large pot of salted water to a boil. Add spaghetti and cook according to package instructions until al dente, about 9-11 minutes.
Drain the spaghetti and divide it among four plates.
Top each plate of spaghetti with meatballs and sauce from the skillet.
Garnish with chopped fresh basil before serving.