01 - Preheat the oven to 375°F.
02 - In a spacious mixing bowl, thoroughly combine the softened cream cheese, sour cream, and mayonnaise until the mixture is completely smooth and homogeneous.
03 - Gently fold in the well-drained spinach, chopped artichoke hearts, minced garlic, shredded mozzarella, grated Parmesan cheese, salt, black pepper, and optional crushed red pepper flakes until all components are uniformly distributed.
04 - Carefully transfer the prepared dip mixture into a 1-quart baking dish, spreading it evenly to ensure consistent baking.
05 - Bake for 20 to 25 minutes, or until the dip is visibly hot, actively bubbling, and the surface achieves a delicate golden-brown hue.
06 - Allow the baked dip to rest for 5 minutes post-oven. Serve warm with an assortment of dippers such as crisp tortilla chips, toasted baguette slices, or fresh crudités.