Preheat oven to 375°. Prick potatoes with a fork and bake for about 1 hour, or microwave for about 15 minutes until soft. Toast pine nuts in a small skillet over medium-low heat, shaking frequently, until lightly browned (about 5 minutes). Carefully scoop out potato centers into a bowl, mash with pesto and olive oil. Mix well. Replace stuffing in each of skins and arrange potatoes in a broiler pan or baking dish. Combine Parmesan with pine nuts, sprinkle on potatoes and brown under broiler for few minutes.