These slow cooker Italian sandwiches make a tasty lunch or dinner. For the filling, mix Italian sausage with ground beef for a hearty Italian hero.
In a large skillet, cook meat, onion, and garlic over medium heat until meat is brown and onion is tender. Drain off fat.
Meanwhile, in a 1 1/2-quart slow cooker, combine ketchup, mushrooms, olives (if desired), and Italian seasoning. Stir in meat mixture.
Cover and cook on low-heat setting* for 4 to 5 hours.
To serve, place half of the cheese evenly on roll bottoms. Spoon meat mixture over cheese. Top with remaining cheese and roll tops.