Lighter chicken cacciatore

Name: Lighter chicken cacciatore
Prep time: 15 min
Cook time: 50 min
Total time: 1 h 5 min
Cuisine: Italian
Ingredients: 1 tbsp olive oil; 3 slices prosciutto, fat removed, chopped; 1 medium onion, chopped; 2 garlic cloves, finely chopped; 2 sagesprigs; 2 rosemarysprigs; 4 skinless chicken breasts(550g total weight), preferably organic; 150ml dry white wine; 400g can plum tomatoesin natural juice; 1 tbsp tomato purée; 225g chestnut mushrooms, quartered or halved if large; small handful chopped flat-leaf parsley, to serve