White Beans with Pasta

Modified from Smitten Kitchen recipe

 I made this for a dinner for students, and it was a big hit, even for non-vegetarians!  Very easy to make for a crowd.   

­­1 medium onion, cut into big chunks
1 medium carrot, in big chunks
1 celery stalk, in big chunks­­­
6 garlic cloves, 4 left whole, 2 finely chopped
1/2 cup olive oil, divided
Coarse or kosh salt

ground pepper to tast
2 to 3 tablespoons tomato paste
3 1/2 cups cooked, drained beans (save cooking liquid for water in recipe, if desired) or 2 15-ounce cans small white beans (such as Great Northern or Cannelini), rinsed
1 pound short tube pasta

A few sprigs of rosemary

• Pulse onion, carrot, celery and whole garlic cloves  in a food processor until finely chopped.
• Heat 1/4 cup oil in a large, heavy pot over medium heat and add vegetable mixture to pot. Season generously with salt.
• Cook, stirring from time to time, until vegetables take on a bit of color, about 10 minutes.
• Add tomato paste and rosemary sprigs and cook it into the vegetables for another minute.
• Add 1 cup water or bean cooking liquid and use it to scrape up any bits stuck to the pot.
• Let simmer until liquid has almost disappeared, about 5 to 8 minutes.
• Add beans and 2 more cups of water (or bean cooking liquid) to the pot and simmer until the flavors meld, about another 15 minutes.
• Meanwhile, cook pasta until al dente and reserve 1 1/2 cups cooking water from your drained pasta.
• Transfer one cup of the bean mixture (not the rosemary sprigs) to your rinsed food processor and purée it until smooth, then stir it back into the sauce to thicken it.
• Add drained pasta and 1/2 cup cooking liquid to bean sauce and cook the mixture together, adding more pasta cooking liquid as needed, until the sauce coats the pasta, about 1 to 2 more minutes.