Heat the oven to 375 F. Butter a small baking dish or spray it with cooking spray.
In a medium bowl, combine the cream cheese, mayonnaise, Parmesan cheese, minced garlic, and garlic powder; stir until smooth and well blended. Add salt and freshly ground black pepper, to taste. Fold in the spinach, chopped artichoke hearts, and half of the shredded mozzarella cheese.
Spoon the mixture into the prepared baking dish and sprinkle the remaining shredded mozzarella cheese over the top.
Bake the dip for 20 to 25 minutes until it is hot and the cheese has melted.
Serve the dip warm with sturdy chips, crackers, or vegetable dippers.