Preheat the oven to 400° F. Wash and dry the potatoes then rub them with olive oil, sprinkle them with salt, and poke them with a fork several times to release steam. Place potatoes on a small baking sheet and bake for 1 hour. Remove from oven and set aside to cool (15-20 minutes).
Once they're cool enough to handle, cut the potatoes in half lengthwise and scoop out the insides, leaving a 1/4 inch rim. Return the potato shells to the oven to 10 minutes to crisp up.
Combine the scooped potato, milk, sour cream, half of the cheese, and 6 tablespoons of the butter (softened). Mash to desired consistency. Stir in the minced parsley, salt, and pepper.
Divide the filling evenly among the shells. Top with the remaining cheese.
Reduce oven temperature to 350° and bake for 30 minutes.
Top potatoes with additional parsley and drizzle with remaining 2 tablespoons of butter, melted.