Preheat the oven to 400 degrees F.
In a small skillet over medium-low heat, add 3 tablespoons olive oil, the butter, garlic, red pepper flakes, and salt and pepper, to taste. Cook to infuse the butter and oil with the garlic, about 4 minutes.
Add the cubed bread to a large bowl, pour the butter
and garlic mixture over the bread and toss to coat. Transfer to a sheet tray and bake until crisp
, about 10 minutes. Remove from the oven and let cool.
In a small bowl whisk
together the remaining olive oil and red wine vinegar
and set aside.
In a large serving bowl, combine the tomatoes
, olives, mozzarella, croutons, basil
, and the oil and vinegar mixture. Gently toss to coat all the tomatoes and croutons. Let the salad sit for 10 minutes before serving.