Place rack in top third of oven; preheat to 425 degrees F. Coat a large rimmed baking sheet with cooking spray. Arrange chicken in a single layer on the baking sheet. Sprinkle the chicken with salt and pepper and spread evenly with pesto. Top with tomato slices and cheese.
Bake until the chicken is cooked through and the cheese is lightly browned and bubbly, 18 to 20 minutes. Top with basil and pine nuts. Serve immediately.
