Grilled Chicken Margherita

4 boneless skinless chicken breasts, pounded to less than 1 inch thickness

salt and pepper to taste

2 tablespoons olive oil

1 teaspoon garlic powder

1 teaspoon Italian seasoning (OR 1/2 teaspoon dried oregano + 1/4 teaspoon dried basil + 1/4 teaspoon dried thyme)

4 slices mozzarella cheese

1/2 cup basil pesto

1/2 cup cherry tomatoes, halved

1 tablespoon fresh lemon juice

1/2 cup packed basil leaves, very thinly sliced

cracked black pepper