Put beans in pot and cover with cold water. Soak for 8 to 10 hours or overnight.
Drain and put beans back into pot with carrot, celery, garlic, whole onion and 8 cups of water. Bring to a boil. Skim surface if necessary.
Reduce heat and simmer for approximately 45 minutes. Check beans for doneness. They should be soft and creamy, not too mushy.
Season beans with salt towards the end of the cooking time.
While the beans are cooking, saute the onion in olive oil in a large skillet until onion is softened. Add the pancetta and continue sauteing until onion and pancetta are golden but not too crispy.
Add the red pepper flakes and season with salt and pepper. Stir in the rosemary and saute for one minute. Remove pan from heat and cover.
Take the beans off the heat once they are cooked. Remove carrot. Throw out celery and onion. Lift out an abundant slotted spoonful of the whole beans and put into the pancetta pan. Take 2 tablespoons of the pancetta mixture and add to bean pot. Cut up the carrot and add to pancetta mixture.
Using an immersion blender, puree the bean mixture until completely smooth. Add the pancetta mixture, stir briefly and bring to a boil.
Stir in pasta pieces and cook until pasta is tender. If soup is too thick, add a little hot water.