Preheat oven to 400. Line a baking sheet with foil or parchment paper, and mist with cooking spray.
Butterfly or slice chicken breasts to create 4 thin cutlets. Season each piece with salt and pepper.
Spoon pesto sauce evenly onto each piece of chicken, and spread. Place in oven, and roast until chicken is cooked through, about 15-18 minutes.
Remove from oven, and top each piece of chicken evenly with tomatoes and mozzarella cheese. Return to oven and cook until cheese is melted, about 5 minutes.
Notes
The entire recipe makes 4 servingsThe serving size is 1 piece of chicken