1. Preheat oven to 400ºF. Scrub potatoes, prick all over with a knife and bake until tender and a knife easily pierces, about 1 hour and 25 minutes. Remove from oven and let rest until cool enough to handle.
2. Cut potatoes in half and scrape out flesh, leaving about 1/4-inch. Cut each half into 3 wedges.
3. Place wedges on a large rimmed baking sheet and mist potatoes with cooking spray. Sprinkle with salt and pepper. Bake for 10 minutes. Turn over and bake 10 minutes longer. Turn once more and bake for a final 10 minutes, until crispy.
4. Mix sour cream with chives, salt and pepper. Serve potato skins with sour cream mixture.