In a large bowl combine chicken breasts, salt, pepper, olive oil, garlic powder, and Italian seasoning. Toss to combine.
To Grill Chicken: Cook chicken over medium-high heat for about 5-7 minutes on each side until cooked through. Top each piece of chicken with 3 tablespoons pizza sauce and a slice of cheese, close grill, and cook another minute or so until cheese is melted. Remove to a plate.
To Cook Chicken on Cook Top: To a large nonstick pan add seasoned chicken breasts. Cook for 4-5 minutes (depends on thickness). Turn over and continue to cook for 4-5 minutes. Remove chicken breasts to a baking pan. Top each breast with 3 tablespoons of pizza sauce and 1 slice of cheese. Place in preheated 400 degrees oven. Bake for 5 minutes, until cheese, is melted. Remove to a serving plate.
In a small bowl, toss together tomatoes, lemon juice, basil, and a little salt and pepper. Top each chicken breast with about 2 tablespoons tomato mixture. Serve immediately or it can be reheated in the microwave or oven.