01 - Preheat oven to 400°F. Lightly grease a 9x13 inch baking dish with olive oil.
02 - Place chicken breasts in prepared dish. Season both sides generously with salt and black pepper.
03 - Spread 1 tablespoon of pesto evenly over the top of each chicken breast.
04 - Arrange tomato slices in a single layer over the pesto-coated chicken.
05 - Top each chicken breast with mozzarella slices. Sprinkle with grated Parmesan if using.
06 - Drizzle remaining olive oil over the entire dish.
07 - Bake for 25-30 minutes until chicken reaches internal temperature of 165°F and cheese is melted and lightly golden.
08 - Remove from oven. Garnish with fresh basil leaves and serve immediately.