Heat the oil in a large stockpot over medium heat. Add the onions, carrots, fennel, and garlic and cook over medium-low heat for 10 minutes, until tender. Add the ciabatta cubes and cook for 5 more minutes. Place the tomatoes in the bowl of a food processor fitted with the steel blade and process just until coarsely chopped. Add the tomatoes to the pot along with the chicken stock, red wine, basil, 1 tablespoon salt, and 1 1/2 teaspoons pepper. Bring the soup to a boil, lower the heat, and allow to simmer, partially covered, for 45 minutes.

Meanwhile, preheat the oven to 375 degrees F.

For the topping, place the ciabatta cubes, pancetta, and basil on a sheet pan large enough to hold them in a single layer. Drizzle with olive oil, sprinkle with salt and pepper, and toss well. Cook, stirring occasionally, for 20 to 25 minutes, until all the ingredients are crisp. The basil leaves will turn dark and crisp, which is perfectly fine. Reheat the soup, if necessary, beat with a wire whisk until the bread is broken up. Stir in the Parmesan and taste for seasoning. Serve hot sprinkled with the topping and drizzled with additional olive oil.