Prick the sweet potatoes with a fork, then place them on a baking sheet & bake for about 35-45 minutes or until they are tender but not mushy, then remove them from the oven & set them on a wire rack to cool, while increasing the oven temperature to broil.
In a medium bowl, combine the Parmesan cheese, parsley, garlic, oregano, rosemary, salt & ground pepper.
When potatoes are cool enough to handle, halve them lengthwise & scoop the flesh out of the skins, leaving a shell from 1/4-inch to 1/2-inch thick. Cut each sweet potato shell lengthwise into 1/2-inch-wide wedges.
Add the skins to the herbed Parmesan mixture & gently toss to combine.
Place the sweet potato wedges on a baking sheet & broil from 4 to 5 inches from the heat for 4 to 6 minutes, or until the cheese is melted & bubbly.