Preheat oven to 375°F. Mix chicken, 1 1/2 cups of the cheese, tomato and Seasoning Mix until well blended.
Arrange tortilla chips on 2 lightly greased foil-lined shallow baking pans, overlapping chips as necessary. Top each pan with 1/2 of the chicken mixture and 1 cup of cheese.
Bake 5 minutes or until cheese is melted. Sprinkle with assorted toppings and serve with guacamole and salsa, if desired.