1. Preheat the oven to 350 degrees. Spread the cubes on a baking sheet. Toss them with a drizzle of olive oil. Bake for 15-20 minutes, until they are just toasted. Set the cubes aside to cool.
2, While the bread is toasting, place the halved tomatoes, cucumbers, and onions in a colander and set it over a large bowl. I usually add in different colors of tomatoes for a pretty presentation. Sprinkle with salt and toss.
3. Whisk the garlic, shallots, dijon, vinegar and pepper. Stream in the ⅓ cup olive oil while whisking until the dressing emulsifies.
4. Place the bread cubes, vegetables, and basil in a bowl. Pour about half of the dressing over top and make sure all the bread cubes are coated. Taste and season with more salt and pepper if desired. Let the mixture sit for 30 minutes.
5. Top with shaved parmesan and additional dressing, to taste. Serve at room temperature.