Preheat oven to 375 degrees F (190 degrees C). Place chicken breasts in a pot of boiling water. Cook until meat shreds easily with a fork, about 20 to 25 minutes. Remove from water, and cool slightly. Remove meat and skin from bones, and shred.

In a medium bowl, combine the cream of mushroom soup and canned tomatoes and mix together.

Lightly coat a 9x13 inch baking dish with cooking spray. In dish begin layering: 1/3 of the chicken, 1/3 of the soup mixture, then crumble tortilla chips on top. Repeat layers twice, ending with tortilla chips and a sprinkle of cheese on top. Bake in the preheated oven for 30 to 45 minutes, until bubbly. Remove from oven and let cool for 5 minutes.

Top casserole with lettuce, chopped tomato, olives, a couple of dollops of sour cream and a sprinkling of chives. Serve.