Pierce chicken breasts with a fork. Pour salad dressing into a large resealable plastic bag; add chicken breasts, seal bag, and shake to coat. Marinate in the refrigerator for at least 1 hour to overnight.
Preheat the oven to 350 degrees F (175 degrees C).
Remove chicken from marinade and place in a lightly greased 9x13-inch baking dish; discard remaining marinade.
Bake in the preheated oven, turning chicken occasionally, until cooked through and juices run clear, about 1 hour. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).
