Spread the spinach and artichoke mixture over the toasted Naan bread leaving a border around the edge. Top with grilled chicken slices ,if desired. Sprinkle with the mozzarella cheese mixture on top. Place in preheated oven and bake until cheese is slightly browned, about 15 minutes or so. Remove from oven and allow to cool. Cut into appetizer size squares with a pizza cutter and serve. Enjoy!