Preheat oven to 400°F. Line a baking sheet with foil or parchment for easy cleanup. Slice chicken breasts horizontally to create 4 thinner cutlets. Season lightly with salt and pepper.

Place the chicken on the prepared baking sheet. Spread about 1 teaspoon of pesto over each piece of chicken.

Bake for 15 minutes or until chicken is no longer pink in the center. Remove from oven; top with tomato slices, mozzarella, and Parmesan cheese. Bake an additional 3-5 minutes until cheese melts.

Optional: For grilling, cook chicken over medium heat until cooked through, then top with pesto, tomatoes, and cheese. Close the grill until the cheese melts.