Place the chicken down onto a baking sheet & season it on both sides with salt, pepper and garlic powder (optional).
Spread the pesto on both sides of the chicken. Add the fresh mozzarella on top of the chicken and top with 1-2 slices of tomato depending on how large the piece is.
Place it into the center rack of the oven for about 30 minutes or until the cheese is melted and the chicken is fully cooked. Serve warm and enjoy!