Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the softened cream cheese, sour cream, and mayonnaise. Mix until smooth and well blended.
Stir in the mozzarella cheese, Parmesan cheese, chopped artichoke hearts, and spinach.
Add the minced garlic, onion powder, salt, black pepper, and red pepper flakes (if using). Mix until all ingredients are evenly incorporated.
Transfer the mixture to a baking dish and spread it out evenly.
Bake in the preheated oven for 25-30 minutes, or until the dip is bubbly and golden on top.
Remove from the oven and let it cool for a few minutes before serving.