Lean ground turkey has just enough fat to give the meatballs some flavor, but little enough to keep them healthful. (Ground turkey breast results in dry meatballs, and regular ground turkey is higher in calories than lean ground beef.) Use a small ice-cream scoop to form the meatballs. Leftovers should be stored in sauce--and served as meatballs heroes.
Bring a large pot of lightly salted water to boil. Add the pasta and cook according to package directions. Drain.
Meanwhile, combine the turkey, breadcrumbs, Parmesan, egg, oregano, thyme and salt in a large bowl and mix thoroughly. Form into 1 1/2-inch meatballs; a small ice-cream scoop makes short work of forming the meatballs and prevents the mixture from getting overworked.
Heat the oil in a deep skillet over medium-high heat. Add the meatballs in a single layer (work in batches if necessary) and brown lightly on all sides, about 6 minutes. Pour in the sauce and simmer gently for 15 minutes.
To serve, place spaghetti on each plate and ladle sauce and meatballs over the top. Sprinkle with chopped fresh herbs if desired.