Rinse samp and place in a large saucepan. Add chicken stock and 300 ml water. Bring to the boil, then reduce heat. Simmer for 30 minutes.
Add cubed butternut, stir well and cook for a further 15 minutes, or until butternut is just tender.
Meanwhile, prepare the chicken. Using a sharp knife, make a lengthways cut through the chicken breast, without cutting right through, to form a pocket.
Chop the apple finely and crumble the cheese. Mix the two together and press into the pockets in the chicken breasts. Secure closed with toothpicks and place breasts in a greased ovenproof dish. Sprinkle with 40ml Parmesan.
Bake in preheated oven for 30 to 40 minutes until cooked through.
Heat butter in a large saucepan.
Add onion and sauté until soft.
Add the drained samp, butternut and sage. Stir-fry for two minutes.
Add wine and remaining Parmesan and simmer gently, stirring, for five minutes.
Dish up individual servings, top with a chicken breast and spoon over sauces from the baking dish.