1.Preheat oven to 200°C/400°F.
2.Heat oil in large flameproof casserole dish over high heat; cook sausages, until browned all over. Drain sausages on paper towel; chop coarsely.
3.Cook onion, pancetta, carrot, celery and garlic in same dish, stirring, 4 minutes or until onion softens. Add paste; cook, stirring, 1 minute.
4.Return sausages to dish with stock, tomatoes, fennel seeds and beans; bring to the boil. Bake, uncovered, 30 minutes.
5.Preheat grill (broiler).
6.Season cassoulet to taste; top with chunks of sourdough. Place under grill until browned lightly. Sprinkle with parsley.