Preheat the oven to 350 degrees F. In a large mixing bowl, add the onion, garlic, turkey, breadcrumbs, salt, pepper, spinach, carrot, egg, and parmesan cheese. Using clean hands, mix until just incorporated (but don't over mix).
Spray a baking sheet with cooking spray. Use a 1 1/2 tablespoon scoop to scoop out some meatball mixture, and gently roll it into a ball. Place on the baking sheet, and repeat with the remaining mixture.
Bake for about 20 minutes until completely cooked through.
When you put the meatballs in the oven, put a pot of water on the stove to boil. Add the pasta, and cook through according to the package directions.
While the pasta is cooking, heat up your marinara (or other sauce) on the stove as well. Once it begins to bubble, reduce it to low to keep warm.
Coat the meatballs with sauce, and toss with pasta. Serve with extra grated parmesan, if desired.
You can try cooking the meatballs by simmering them in the sauce.
If you're looking for a prepared marinara sauce, I recommend Rao's. It's the best I've ever had.
Calorie information is for the meatballs. It does not include sauce or pasta.