Place bread in a food processor, and pulse 10 times or until crumbs measure 1 1/3 cups. Combine the crumbs, beef, and next 7 ingredients (beef through garlic) in a large bowl, and shape meat mixture into a 9 x 6-inch loaf. Place loaf in an electric slow cooker.
Combine ketchup, mustard, and pepper in a small bowl, stirring with a fork. Spread ketchup mixture evenly over top of loaf. Cover with lid; cook on LOW for 5 hours.