Preheat the oven to 375°F (190°C).
In a large bowl, mix cream cheese, sour cream, and garlic until smooth.
Add spinach, artichokes, Parmesan, and ½ cup mozzarella. Stir to combine.
Season with salt, pepper, and red pepper flakes (if using).
Transfer the mixture to a baking dish and top with the remaining mozzarella.
Bake for 20-25 minutes, or until bubbly and golden.
Let cool for 5 minutes, then serve with chips, bread, or veggies.