01 - Preheat the oven to 350°F (180°C).
02 - In a large mixing bowl, blend cream cheese, sour cream, and mayonnaise until the mixture is smooth.
03 - Add shredded mozzarella, grated Parmesan, spinach, artichoke hearts, minced garlic, salt, black pepper, and crushed red pepper flakes if desired. Stir until evenly distributed.
04 - Transfer the mixture into a medium baking dish and spread evenly across the surface.
05 - Place the baking dish in the oven and bake for 20 to 25 minutes until the top is golden and the contents are hot and bubbly.
06 - While baking the dip, arrange baguette slices on a baking tray and toast in the oven for 5 to 7 minutes until crisp and lightly golden.
07 - Serve the hot dip alongside toasted baguette slices for dipping.