01 - Set the oven temperature to 350°F (180°C) to prepare for baking the dip.
02 - In a large mixing bowl, blend cream cheese, sour cream, and mayonnaise until smooth and uniform.
03 - Fold in shredded mozzarella, grated Parmesan, thawed spinach, chopped artichoke hearts, minced garlic, salt, black pepper, and optional red pepper flakes until thoroughly incorporated.
04 - Transfer the mixture into a medium baking dish and spread evenly to ensure uniform cooking.
05 - Bake in the preheated oven for 20 to 25 minutes, until the dip is hot, bubbly, and the surface is lightly golden.
06 - Place baguette slices on a baking tray and toast in the oven for 5 to 7 minutes, until crisp and lightly golden brown.
07 - Serve the dip warm with the toasted baguette slices on the side for dipping.