Preheat oven to 350° F. Grease 2-quart baking dish.
Combine macaroni and cheese, salsa, chiles, crabmeat, chili powder and cumin in medium bowl. Transfer to prepared baking dish.
Bake for 25 minutes or until bubbly around edges; top with crushed tortilla chips and Monterey Jack cheese and cheddar cheese.
Bake for 5 to 10 minutes or until tortilla chips are golden brown and the cheese. Sprinkle with green onion.