01 - Set the oven to 350°F (180°C) to preheat.
02 - In a large mixing bowl, blend cream cheese, sour cream, and mayonnaise until smooth and creamy.
03 - Fold in Parmesan, mozzarella, thawed spinach, minced garlic, and spring onions. Season with salt, black pepper, nutmeg, and cayenne pepper, mixing thoroughly.
04 - Transfer the mixture evenly to a medium-sized baking dish.
05 - Bake for 20 minutes until the top is bubbling and lightly golden.
06 - Serve warm alongside toasted bread, crackers, or vegetable sticks.