Spray a 9x13 baking dish (or aluminum pan if freezing) with your preferred cooking spray.
Place diced cooked chicken into the dish. Pour in marinara sauce and add the Italian seasoning and salt and pepper. Mix to combine, until the chicken is thoroughly coated with the sauce.
Spread chicken layer evenly across bottom of pan or dish.
Sprinkle mozzarella cheese on top of chicken mixture, then top with the Parmesan cheese.
In a small bowl, add the first three breadcrumb topping ingredients and stir gently with a fork. Add the olive oil, and toss with fork until breadcrumbs are evenly coated but not sticky or clumping.
Gently sprinkle breadcrumb topping over the Parmesan cheese layer.
To freeze:
Wrap or cover dish, label, and place into freezer. Be sure to include date made and heating instructions.
Will keep in freezer for 3-6 months.
To heat:
Remove from freezer and allow to thaw overnight in the refrigerator.
Bake at 350 degrees Fahrenheit for 25-30 minutes, until bubbly and breadcrumbs are toasted and golden brown.
Serve by itself or on top of pasta or rice. And don't forget the green salad!
Notes
I have not tested this, but you can try heating from frozen - double your cook time to about 60 minutes - bake covered for the first 30 minutes, and then uncovered for the last 30 minutes.For low-carb/keto, leave off the breadcrumb layer either on a portion or all of it. Use a low-carb pasta or marinara sauce to keep the carb count low. Serve over low-carb pasta, riced cauliflower, or just savor it straight up if you prefer!