In a large bowl combine chicken, salt and pepper, olive oil, garlic power, and Italian seasoning. Toss to combine. Grill chicken over medium-high heat for about 6-8 minutes on each side until cooked through. Top each piece of chicken with a slice of mozzarella cheese and cook another minute or so until melted. Toss tomatoes, lemon juice, and basil together. Top each chicken breast with about 3 tablespoons pesto, a scoop of tomatoes, and some freshly cracked black pepper. Serve immediately.