01 - Preheat oven to 375°F (190°C).
02 - In a large bowl, blend cream cheese, sour cream, and mayonnaise until smooth.
03 - Incorporate Parmesan, mozzarella, spinach, artichoke hearts, garlic, salt, black pepper, and red pepper flakes (if using). Stir until evenly combined.
04 - Spread the mixture evenly into a medium baking dish.
05 - Bake for 20 to 25 minutes until hot, bubbly, and lightly golden on top.
06 - Allow to cool for 5 minutes before serving warm with toasted baguette slices.