In a mixing bowl, combine the cream cheese, sour cream, mayonnaise, Parmesan cheese, mozzarella cheese, garlic, salt, and pepper. Mix until well combined.
Stir in the thawed and drained spinach until evenly distributed.
Transfer the mixture to a baking dish and spread it out evenly.
Bake in the preheated oven for 20 minutes, or until the top is golden and bubbly.
Remove from the oven and let it cool slightly before serving. Enjoy with chips, bread, or veggies!