Place chicken into bottom of slow cooker.
Stir together marinara, tomatoes, garlic and Italian seasoning; pour over chicken.
Cover, and cook on low 5-6 hours or until chicken is tender.
Sprinkle Parmesan over top of chicken, cover and cook on high an additional 30 minutes to melt cheese.
In a medium skillet, melt butter; add bread crumbs and garlic salt. Cook 4 minutes or until golden brown; stirring often.
Before serving, sprinkle bread crumb mixture and a sprinkle of shredded mozzarella cheese over chicken. Serve with pasta, if desired.