Start with adding the carrots, celery, and onion to a food processor with the regular blade.
In a large pot, heat the olive oil over medium heat. Add the chopped onions, carrots and celery and cook over medium-low heat for 10 minutes, stirring occasionally, until soft.
Add the garlic and cook for another minute.
Stir in the chicken stock, tomatoes and salt and pepper to taste.
Bring the soup to a boil, then lower the heat and simmer for 20 minutes.
remove from the heat, add the Parmesan cheese and using a hand blender puree the soup.
For the Croutons:
Heat your broiler/grill to medium high heat. Place the toasted bread on a cookie sheet and butter them.
Spread the cheese evenly over the slices and place under the broiler/grill for 30 seconds to 1 minute (until melted and golden brown)
Place on a cutting board, allow to rest for 1 minute and cut into 1-inch cubes.
Serve the soup with a dollop of red pesto and warm cheesy croutons.
Notes
When cooking the garlic, be careful not to let it brown too much. Burned garlic will taste bitter and change the flavor of the soup.
For added intensity of tomato flavor add a tablespoon of tomato paste to the tomatoes before adding the stock.