Cut off the top of the bread. Use your fingers to remove the crumb from the center of the bread, leaving only the crust as a wall (discard the crumb or reserve it for another use, such as making breadcrumbs).
Melt the butter in a medium skillet over medium heat, then add the shallots, garlic and red pepper flakes. Cook, stirring occasionally, until softened about 3 minutes. Add the spinach and artichokes and cook, stirring, until hot, about 3 minutes. Add the cream cheese and cook, stirring, until melted. Stir in the mozzarella and season with salt and pepper.
Spoon the mixture into the bread bowl, mounding it slightly if necessary, and sprinkle with the Parmesan. Place the bread and the top side by side on a baking sheet and bake until the bread is hot and crusty and the top of the spinach dip is lightly browned, about 15 minutes. Transfer the bread bowl to a serving platter. Tear the top of the bread into chunks and serve alongside the dip with crudites for dipping.