French Onion Meatball Sandwich is a savory and satisfying sandwich that combines juicy meatballs with caramelized onions and melted cheese. The meatballs are made with ground beef, breadcrumbs, and spices, then simmered in a flavorful French onion sauce. The sandwich is assembled with a toasted roll, meatballs, onions, and cheese, then broiled until the cheese is melted and bubbly. It is a perfect lunch or dinner option for meatball and sandwich lovers.