In a large oven proof skillet, heat olive oil over medium-high heat. Season chicken on both sides with salt and pepper. Sear chicken for 3-5 minutes on each side.
Place the skillet in the oven and cook uncovered for 25-30 minutes or until a meat thermometer reads 165-170 degrees when inserted in the center.
Remove pan from the oven. Liberally smear on pesto, cover with one slice of cheese, top with tomatoes, and season with pepper. Return pan to the oven and cook for 3-5 minutes more, just until cheese is melted.