Preheat oven to 450°. Thinly slice 6 Grilled Spicy Cilantro Chicken thighs. Place naan breads on a parchment paper-lined baking sheet; spread each with 1 Tbsp. reserved cilantro mixture. Layer each with 1/2 cup sliced chicken, 4 reserved plum tomato halves, and fresh mozzarella cheese slices. Bake 7 to 8 minutes or until cheese melts. Top with arugula. Serve with remaining cilantro mixture.