Position the oven rack at the top level, closest to the broiler flame. Preheat the broiler according to manufacturer’s instructions.
Meanwhile, prepare the mango topping by combining the mangoes, cilantro, jalapeno, and red onion. Set aside.
Sprinkle each un-cut pita bread with 1/3 cup Fontina cheese. Place on a cookie sheet and broil for 2 minutes until the cheese is melted.
Transfer the pitas to a serving platter. Top each with a ½ cup of spinach followed by a scoop of the mango salad. Garnish with diced tomato and serve immediately.