Step 1

In a large Dutch oven or soup pot, heat the butter and 2 tablespoons of the olive oil over medium heat. Add the onion, celery, and carrots, and cook, stirring occasionally, until softened, 6 to 8 minutes. Stir in the garlic and cook for another minute until fragrant; do not brown.

Step 2

Pour in the chicken stock, then add the tomatoes, tomato paste, cannellini beans, potatoes, salt, sugar, thyme, oregano, and pepper. Bring the mixture to a boil, then reduce the heat to low, cover, and simmer gently for about 20 minutes.

Step 3

Use a ladle to scoop out about one cup of the beans, veggies, and a bit of broth and transfer it to a blender. Remove the center knob to let the steam escape, and cover the opening with a paper towel or kitchen towel to avoid splatters. Purée until smooth and set aside.

Step 4

Add the pasta and zucchini to the pot and stir to combine. Bring back to a boil, then reduce the heat to low and continue cooking, covered and stirring occasionally so the pasta doesn’t stick to the pot, for about 15 minutes, or until the pasta is al dente and the zucchini is tender.

Step 5

Add the reserved purée back to the pot, then stir in the remaining tablespoon of olive oil, the cheese, and basil (if using). Taste and adjust seasoning with salt and pepper, if necessary (I usually add at least ¼ teaspoon more salt, but it will depend on the saltiness of your chicken stock). Ladle the soup into bowls and top with more cheese, if desired.