Heat oven to 425°F. Pierce potatoes with fork. Bake 1 hour or until tender. Cool 30 minutes.
Cut each potato lengthwise in half; carefully scoop out potato pulp, leaving 1/4-inch shells. (Save potato pulp for another use.) Place potato shells, skin sides down, on cookie sheet. Spray potato shells with cooking spray. Sprinkle evenly with taco seasoning mix and cheeses.
Bake 10 minutes or until cheese is melted.
Serve potato skins with sour cream. Sprinkle with chiles, onions and pepper.