How to Make It
In a large saucepan, bring the stock to a boil with the prosciutto. Add the orzo, cover partially and cook until the orzo is al dente, about 6 minutes. Strain the broth into a heatproof bowl. Pick out the prosciutto and dice it. Reserve the orzo separately.
Wipe out the saucepan and heat the olive oil in it. Add the onion, carrot, celery, garlic, rosemary, crushed red pepper and diced prosciutto and cook over moderately high heat, stirring occasionally, until the vegetables are lightly browned, about 6 minutes. Add the tomato paste and the strained broth, cover partially and simmer until the prosciutto and vegetables are tender, about 8 minutes. Discard the rosemary sprig.
Add half of the beans to the soup. Puree the soup in a blender and return to the saucepan. Add the remaining beans and the reserved orzo and cook until heated through. Season the soup with salt and pepper. Stir in the goat cheese and serve.