In a medium mixing bowl, combine the softened cream cheese, sour cream, and mayonnaise. Mix until smooth and well incorporated.
Add the thawed spinach, chopped artichokes, minced garlic, red pepper flakes (if using), and half of the mozzarella and Parmesan cheeses to the cream cheese mixture.
Stir until all ingredients are evenly mixed. Season with salt and pepper to taste.
Transfer the mixture into a baking dish and spread it evenly.
Top with the remaining mozzarella and Parmesan cheeses.
Bake in the preheated oven for 25-30 minutes, or until the top is bubbly and golden brown.
Remove from the oven and let it cool slightly before serving.
Notes
Serve warm with tortilla chips or sliced baguette. Garnish with parsley for presentation.