Preheat oven to 350 degrees F. Boil chicken breasts until cooked thoroughly, then shred. Place chicken a mixing bowl.
Add to bowl, cream of mushroom soup, cream of chicken soup, Ro*Tel, chopped onion, 16 oz. Kraft Cheese, cumin powder, and 10 oz. crushed Doritos Chips. Add salt and pepper to taste. Mix all ingredients thoroughly with a large mixing spoon.
Lightly grease a casserole dish and spread the remainder of the crushed Doritos across the bottom of the casserole dish evenly. Add chicken mixture on top of crushed Doritos and spread evenly. Add remainder of Kraft Shredded Mexican Four Cheese and top with chopped black olives.
Bake for 40 minutes or until cheese is bubbling in middle of casserole.