Heat a large Dutch oven or soup pot over medium heat. Add the oil, butter, onion, shallot, celery, and bell pepper and stir to combine. Cook for 4-5 minutes or until the onions are translucent, stirring occasionally.

Add the garlic, stir well and cook for another 2 minutes.

Add the broth, carrots, parmesan rind (if using), and salt. Bring the mixture to a boil then reduce to a steady simmer and cook for 20-25 minutes (uncovered) or until the veggies are nice and tender.

With a slotted spoon, remove 2 cups of the diced veggies and set aside.

With an immersion blender (or a regular blender), puree the broth/veggie mixture in the pot until smooth. If using a regular blender, let the mixture cool down a bit before blending and remove the center cap on the blender top, covering it with a clean kitchen towel or several thicknesses of paper towels to allow heat to vent.

Add the pasta, bring the mixture to a boil then reduce to a steady simmer. Cook, uncovered for whatever the time on your bag or box of pastina instructs.

Add the rotisserie (or leftover) chicken and the reserved veggies. Stir to combine. Cover and allow the soup to rest for 20 minutes.

Taste the soup and adjust the seasoning, adding more salt if needed.

Serve with grated parmesan, a scatter of finely chopped fresh rosemary or fresh thyme leaves (or both) and fresh ground black pepper.