1Set oven control to broil. Line cookie sheet with foil. Place poblano chiles on cookie sheet. Broil 8 minutes, turning once, until blackened. Place blackened chiles in bowl; cover tightly. Let stand 10 minutes. Peel off charred skin from chiles.
2Heat oven to 350°F. In large bowl, mix mashed potatoes, 1 cup of the corn, the cilantro, green chiles, cumin and 1/2 cup of the cheese. Cut slit down center of each poblano; stuff with potato mixture. Place in shallow baking dish. Sprinkle with remaining 1/4 cup corn and 1/4 cup cheese.
3Bake uncovered 15 minutes or until cheese is melted and tops are lightly browned.