Preheat the oven to 375°F (190°C).
Place the bread cubes in a large bowl. Toss with 2 tablespoons olive oil, Italian seasoning, garlic powder, onion powder, salt, and pepper until evenly coated.
Spread the bread onto a baking sheet and bake for 5–7 minutes, or until lightly golden and crisp. Let cool slightly.
In a small bowl, whisk together the ¼ cup olive oil, red wine vinegar, minced garlic, salt, and pepper.
In a large serving bowl, combine the tomatoes, cucumber, red onion, basil, and mozzarella (if using).
Add the toasted bread cubes and pour the dressing over the salad. Toss gently until everything is evenly coated.
Let the salad sit for 10–15 minutes so the bread absorbs the dressing while still retaining a little texture. Taste and adjust the seasoning with additional salt and pepper if needed. Garnish with extra basil or shaved Parmesan before serving.