01 - Set oven temperature to 350°F.
02 - In a large bowl, blend cream cheese, sour cream, and mayonnaise until smooth.
03 - Fold in mozzarella, Parmesan, spinach, artichoke hearts, garlic, salt, black pepper, and red pepper flakes if using until fully combined.
04 - Transfer mixture into a medium baking dish, spreading it evenly.
05 - Bake for 20 to 25 minutes until heated through with a golden, bubbling surface.
06 - Place baguette slices on a baking tray and toast in the oven for 5 to 7 minutes until crisp and lightly golden.
07 - Present the warm dip alongside toasted baguette slices.