PREHEAT oven to 350° F. Lightly grease 2 1/2-quart casserole dish.
COOK macaroni in large saucepan according to package directions; drain. Return to saucepan.
ADD cheddar cheese, 1 1/2 cups Pepper Jack cheese, evaporated milk and black pepper to macaroni; stir until combined. Pour into prepared casserole dish. Combine remaining 1/2 cup Pepper Jack cheese, tortilla chips and red pepper flakes in small bowl. Sprinkle over top. Cover tightly with foil.
BAKE for 20 minutes. Uncover; bake for an additional 10 minutes or until lightly browned.