Slow Cooker Chicken Parmesan Sandwiches

crushed tomatoes

diced tomatoes (drained)

tomato paste

shredded parmesan cheese

large onion (diced)

garlic cloves (minced)

oregano

basil

bay leaves

boneless (skinless chicken breasts)

slices mozzarella cheese

buns or rolls

additional Parmesan cheese to garnish (if desired)