01 - Set the oven temperature to 375°F (190°C).
02 - In a large mixing bowl, blend cream cheese, sour cream, and mayonnaise until smooth and well incorporated.
03 - Fold in shredded mozzarella, parmesan, and cheddar, reserving ¼ cup mozzarella and 2 tablespoons parmesan for topping.
04 - Mix in the thawed, drained spinach, chopped artichokes, and minced garlic. Season with salt, pepper, and optional red pepper flakes, stirring thoroughly.
05 - Transfer the mixture into a 1.5-quart baking dish, smoothing the surface evenly, then sprinkle the reserved mozzarella and parmesan on top.
06 - Bake for 20 to 25 minutes until the dip is hot, bubbly, and the cheese topping turns golden brown.
07 - Allow to rest for 5 minutes before serving warm alongside tortilla chips.