Preheat oven to 350°F. Grease an 8×8 inch casserole dish with cooking spray.
Layer the fully-cooked chicken in the bottom. Dump in the marinara sauce and mix with the chicken. Next, top with both cheeses until all the chicken is covered.
In a small bowl, stir together the breadcrumbs, olive oil, fresh parsley, and a pinch of salt and pepper.
Sprinkle the seasoned breadcrumbs over the top. (Freezing instructions begin here.)
Bake for about 20-25 minutes or until golden on top and bubbling on the sides. If you want it a little more browned on top, turn on the broiler for 1-2 minutes (watch closely so it doesn’t burn!). Serve “as is” or over your favorite cooked pasta or rice.
