Preheat oven to 350F. In a large bowl, thoroughly mix the mayonnaise, Parmesan, artichoke, mozzarella and garlic powder. Transfer the mixture to an 8� x 8� baking dish. Bake 30 minutes, or until the surface is golden brown and bubbly. Sprinkle with paprika and serve immediately. Because of all the cheese, if this cools down it can easily be reheated in the oven at 350F just until the cheese melts again.