01 - Preheat the oven to 375°F. Lightly grease an 8-inch square baking dish or a dish of similar size.
02 - In a large mixing bowl, beat together softened cream cheese, sour cream, and mayonnaise until smooth and creamy.
03 - Stir in shredded mozzarella, grated Parmesan, thawed spinach, chopped artichoke hearts, minced garlic, salt, black pepper, red pepper flakes if using, and onion powder until fully incorporated.
04 - Spread the mixture evenly into the prepared baking dish.
05 - Bake for 20 to 25 minutes until the dip is hot, bubbly, and slightly golden on top.
06 - Serve warm accompanied by tortilla chips, sliced baguette, crackers, or fresh vegetables.