1. Combine turkey, 1/2 cup cheese, parsley, breadcrumbs, egg, 1/2 teaspoon salt and 1/4 teaspoon pepper in a bowl, and form into 15 meatballs. Place meatballs on a plate and reserve.
2. Heat oil in a large saucepan over medium-high heat. Add onion and cook until soft, 5 minutes. Add garlic, and cook an additional 2 minutes.
3. Add tomatoes, beans, and remaining salt and pepper; bring to a boil.
4. Add meatballs; return to a boil. Reduce heat and simmer on low heat until meatballs are cooked through and sauce has thickened, 15 minutes.
5. Divide spaghetti among 5 bowls, then divide meatballs and sauce among bowls. Garnish with additional parsley and remaining 1/4 cup cheese.