Slice the baked potatoes in half lengthwise. Using a spoon, scoop out the centers and place into a medium bowl, leaving a 1/4" thick shell. Place the potato shells onto a foil-lined baking sheet. Mash the potato centers with the remaining ingredients except Parmesan cheese until smooth and creamy. Spoon the mixture evenly into the potato shells. Sprinkle with grated Parmesan cheese. Bake in preheated 350 degree oven for 20 minutes, or until heated through.