Combine the soup and tomatoes in a separate bowl. Then, in the bottom of a square baking dish, sprinkle 1/3 of the tortilla strips evenly along the bottom.
Lay half of the chicken over the tortilla stips, and then spoon half of the soup & tomato mixture over the chicken.
Repeat the layers once more, and sprinkle the top with the leftover tortilla strips, and top with the fat free cheddar cheese. You may not need to use the whole cup of cheese, just use however much you think is best.
Baked, covered, at 350 degrees for 40 minutes or until the cheese on top is bubbly. Then, uncover the casserole and cook for 5 more minutes.
