For the garlic bread croutons: Preheat the oven to 425 degrees F.
Toss the cubed garlic bread with the Parmesan and place on a baking sheet. Bake until golden and crisp, 7 to 8 minutes. Set aside.
For the soup: In a saucepot over medium heat, add the olive oil and jarred pesto. Cook the pesto for a couple minutes to allow the flavors to come out. Add the tomato soup, diced tomatoes, Parmesan, sherry, dried parsley and about half the amount of water listed in the soup can instructions. Season with salt and pepper. Bring to a simmer and simmer until heated through. Stir in the cream.
Serve the soup in bowls and top with the garlic bread croutons. Sprinkle over some additional Parmesan and drizzle with pesto. Serve extra croutons on the side.