1. Preheat oven to 450ºF. Line a large baking sheet with foil. Prick potatoes all over with a fork and bake until very soft, 1 hour 15 minutes to 1 hour 30 minutes. Let cool. Lower oven temperature to 350ºF.
2. Cut potatoes in half crosswise and scoop out flesh. In a food processor, puree potato flesh with chilies, sauce, butter and salt. Spread into a greased 2-quart baking dish.
3. Bake uncovered until hot, 40 to 45 minutes. Serve.