Preheat oven to 350 F. Place cooked and diced chicken in a large bowl and mix with cream of mushroom soup and rotel.
Spread half of the crushed doritos in the bottom of a large greased baking dish. Spread the chicken mixture over the crushed chips.
Sprinkle shredded cheddar cheese on top and top with the remaining half of crushed doritos chips. Bake for 20-25 minutes.