Preheat the oven to 200°C. Split the chicken breasts down the middle, making a pocket in each and spoon in the herbed cream cheese. Close the pocket then wrap each chicken breast in a slice of Parma ham to contain the cheese. Place the chicken in a non-stick ovenproof dish and bake for 15 minutes until the chicken is thoroughly cooked and the juices run clear when tested with a skewer. Leave to cool slightly and then cut the chicken into 3 thick slices. Meanwhile, peel and slice the vegetables. Place on a baking tray, drizzle with oil and season with salt and pepper. Bake in the oven for 15 minutes. To prepare the mash, boil the sweet potatoes in hot salted water till cooked through. Drain and mash together with the milk and butter and season with salt and pepper. Serve the sliced stuffed chicken on top of sweet potato with the roasted vegetables on the side.