Place chicken breasts in a resealable gallon-sized bag and pour the Italian dressing on top. Seal the bag, removing as much of the air as possible. (If desired, place bag in a bread loaf pan to ensure chicken is fully submerged in marinade.)
Place pan in fridge and marinate for at least 1 hour (or up to 12 hours).
When finished marinating, spray a 9 x 13 inch baking pan with non-stick cooking spray.
Spread 1/2 cup of marinara sauce in the bottom of the pan.
Remove chicken from marinade (discard marinade) and place in pan.
Top chicken with remaining marinara sauce and bake for 20 minutes at 350 degrees.
Remove chicken from oven and top with cheese and toppings of choice.
Place chicken back in oven and bake for about 10-15 more minutes or until chicken is no longer pink on the inside and the internal temperature reaches 165 degrees.