Boil the chicken breast. (I added celcery, carrots, and an onion so that I could use the broth later for soup or fried rice.) After the chicken is cooked allow to cool so that it can be shreaded.
I'm not a fan of crunchy onions so I always sauté them first with a little butter or margerine but this can be done in the same pot you use to cook the chicken mixture.
In a large pot add the chicken, rotel tomatoes (I use the generic ones), cream of chicken soup, onion and the sour cream and cook until warm and bubbly. (You can substitute one can of cream of mushroom if you prefer)
Cut tortillas into quarters. In a large 3 quart baking pan place one layer of tortillas into the bottom of pan. Next spoon on a layer of the chicken mixture. Top this with a layer of the cheese. I used 1 lb of Monzeralla and 1 lb of Monterray Jack mixed together. Then repeat layers until all ingredients are used up.
Bake at 350 for 45 minutes. I covered mine with aluminum foil to prevent the top from drying out. Let it set and cool for approximately 10-20 minutes then cut and serve.
Some additions or changes: you could serve with salsa, sour cream, or what ever you like. I'm thinking of adding ranch dressing next time I make it and even possibly some bacon crumbles. Also, you could use corn tortilla's instead of the flower ones. Enjoy!