Put the tomatoes on a rimmed baking sheet, toss with 2 tablespoons of the garlic oil and season with salt and pepper, to taste. Roast until the tomatoes are softened and the edges are beginning to brown, 15 to 20 minutes.
Meanwhile, heat 1 tablespoon of the garlic oil in a saucepan over medium-high heat. Add the basil and stir for about 30 seconds. Add the canned tomatoes with their juice and the water; season with salt and pepper, to taste. Bring to a boil, then reduce the heat to medium-low and simmer for 15 minutes. Stir in the bread and simmer for 2 to 3 minutes.
Stir the oven-roasted tomatoes and any cooking juices into the saucepan and simmer for another 3 minutes. Taste for seasoning, adjusting if necessary, and ladle into serving bowls. Garnish with a drizzle of garlic olive oil and basil leaves.