Warm 3 tbsp olive oil in a 26 cm / 5-quart Dutch oven over medium heat. Add onion, celery, and carrot, and cook for 6 to 7 minutes, stirring occasionally, until softened and translucent.
Add garlic and rosemary and cook for 1 minute until fragrant.
Stir in tomato paste and red pepper flakes if using, and cook for 1 to 2 minutes until the paste darkens slightly.
Add the drained chickpeas. Use a potato masher or the back of a wooden spoon to mash about a third of them right in the pot, leaving the rest whole.
Pour in the broth and add the parmesan rind if using. Bring to a simmer, then partially cover and cook for 15 minutes to let the flavors come together.
Remove and discard the rosemary sprig and parmesan rind. Season with 1 tsp salt.
Keep the pot at a steady simmer and stir in the pasta. Cook uncovered for 8 to 10 minutes, stirring occasionally, until al dente, checking a minute before the package time since it keeps cooking in the hot broth.
Remove from heat once the pasta is al dente. The stew will continue to thicken as it sits.
Ladle into bowls, drizzle with olive oil, and finish with black pepper, chopped parsley, and grated parmesan or pecorino.