1. Preheat oven to 400°.
2. Place bread in a food processor; pulse 10 times or until coarse crumbs measure 1/2 cup. Transfer to a bowl; set aside.
3. Place garlic, onion, and parsley in processor; pulse 20 seconds or until chopped. Add breadcrumbs, ground round, and next 6 ingredients. Pulse 1 minute or until mixture is combined, stopping frequently to scrape down sides.
4. Line a broiler pan with foil. Shape meat mixture into 48 (1 1/2-inch) balls. Place meatballs on broiler rack coated with cooking spray. Bake at 400° for 12 minutes or until meatballs are no longer pink in center.
5. While meatballs cook, cook pasta according to package directions, omitting salt and fat.
6. Bring pasta sauce to a simmer in a large saucepan. Add meatballs, and simmer 10 minutes or until sauce reaches desired consistency. Serve over spaghetti. Garnish with chopped parsley, and serve with additional Parmesan cheese, if desired.