Heat a grill or skillet over medium heat. Generously butter one side of the bread.
Place the bread in the skillet, butter side down. Cook for approximately 1 minute or until the bread is golden.
Remove from the skillet and place the bread cooked side down. Spread the pesto generously on each slice of the bread.
Top one side of the sandwich with mozzarella, tomato slices, a generous drizzle of good olive oil, salt and pepper to taste.
Top with basil leaves and the second slice of bread.
Serving: 1 Sandwich, Calories: 537kcal, Carbohydrates: 46.4g, Protein: 11.4g, Fat: 30g, Cholesterol: 36mg, Sodium: 903mg, Fiber: 2.3g, Sugar: 5.8g