Preheat the oven to 350°F (180°C or gas mark 4) and scatter the zucchini, eggplant, peppers and onion pieces onto the sheet pan. Drizzle the vegetables with 1 tablespoon (15 ml) of the olive oil, season with ¼ teaspoon of the salt and place into the oven to bake for 20 minutes.
Meanwhile, in a bowl, combine the canned tomatoes, garlic, 1 teaspoon of the oregano, tomato paste, balsamic vinegar and black olives.
Put the bread chunks in a small bowl and drizzle with the remaining 1 tablespoon (15 ml) of oil and ½ teaspoon of oregano. Toss to combine.
After the veggies have baked for 20 minutes, remove the pan from the oven and pour the tomato mixture over the veggies. Use a spatula to coat the vegetables in the sauce and then place the vine or cherry tomatoes on top. Place the pan back into the oven to bake for 15 minutes.
Remove the pan from the oven and add the bread chunks to the pan. Return the pan to the oven to bake for a final 10 minutes, until the bread chunks have hardened and turned crispy. Garnish with fresh basil and serve.