Roasting the heirloom tomatoes, onion, and garlic intensifies their flavors by caramelizing their natural sugars. Sweet basil and crushed red pepper flakes add just the right amount of seasoning and warmth when blended with the caramelized tomato mixture to make a flavorful chunky soup. Simply baking Parmigiano Reggiano melts and browns the cheese into a crunchy treat. I like to eat a spoonful of chunky tomato basil soup followed with a bite of the crispy cheese. —Garden Gate Kate
Preheat oven to 400 degrees F. Line a baking sheet with parchment paper. On baking sheet, place a heaping tablespoons of the grated parmigiano and flatten with your hand. Make parmigiano clusters 4 inches apart to allow for spreading. Bake for 5 minutes. Allow 30 minutes to cool.
Raise the oven to 450 degrees. Spread tomatoes, onions, and garlic onto a baking tray. Drizzle with olive oil and stir to coat. Season with sea salt and pepper. Roast for 20 to 30 minutes until caramelized.
Transfer the roasted tomatoes, onion and garlic mixture into a large pot including all the roasting liquid. Add chicken broth and red pepper flakes to pot. Bring to a boil and simmer, uncovered for 15 minutes. Add chopped basil leaves. Puree the soup with an immersion blender or in batches in a food processor until slightly chunky. Season with sea salt and pepper. The soup freezes well and can be reheated at a later time. Serve chunky tomato basil soup with Parmigiano cheese crisps.