Preheat oven to 375°F.
In large mixer bowl, beat mayo, cream cheese, garlic salt and chili powder on medium speed, scraping bowl often, until smooth (1-2 minutes).
By hand, stir in 1 cup cheese (reserving 1 cup for top), artichoke hearts, and spinach.
Spread artichoke mixture in 9 inch pie pan or baking dish.
Sprinkle with remaining cheese.
Bake for 15-20 minutes or until cheese on top melts
Serve with tortilla chips.