In a large (6 quart) slow cooker, place half of the crushed tomatoes, Italian seasoning, garlic, and salt. Place chicken breasts inside the slow cooker, top with half of the mozzarella and Parmesan cheese, and pour remaining crushed tomatoes on top.
Cover the slow cooker and cook, on low for 8 hours or 4 on high.
Toast the breadcrumbs:
Meanwhile, heat the broiler and line a baking sheet with foil. In a small bowl, combine panko breadcrumbs with olive oil and a pinch of salt and pepper.
Spread in a thin, even layer on a foil-lined baking sheet. Broil 3 to 5 minutes, stirring occasionally until breadcrumbs are evenly golden brown.
Cook the pasta:
If serving chicken parmesan with pasta, 10-15 minutes prior to serving, boil the pasta.
Serve:
When chicken is cooked through to an internal temperature of 165F, sprinkle remaining mozzarella cheese over top.
Serve in bowls over pasta, if desired, topping the chicken with breadcrumbs and remaining Parmesan cheese.
Notes
If you need to make this recipe gluten-free, crush Chex rice cereal into a crumbly mixture and use that as a replacement for panko crumbs.