In large bowl, mix beef, egg, bread crumbs, milk and herb blend. Shape into 16 meatballs. Spray 4- to 5-quart slow cooker with cooking spray. Add marinara sauce and meatballs to slow cooker. Cover; cook on High heat setting 3 to 4 hours.
Meanwhile, heat oven to 350°F. Cut dough into four pieces. Spray underside of jumbo muffin pan. Form dough around muffin cups to make four bowls. Bake 13 to 15 minutes or until bowls are golden brown. Cool slightly. Remove bowls, and cool completely.
To serve, spoon 4 meatballs and sauce into each bread bowl. Sprinkle with Parmesan cheese, if desired.