Line an eight-inch square pan with foil or wax paper. Spray the foil or paper with nonstick spray and set aside. Heat a grill to medium heat or preheat the oven to 350ºF. Wash the peppers, cut off and discard the tops, and clean the insides of all seeds and membrane. To make the filling, heat the oil in a medium nonstick skillet over medium heat. Sauté the green onion, tomato, and corn with the garlic powder, salt, and pepper until soft, about four minutes. Fold in the white rice and diced chicken. Remove from heat. Allow filling to cool and stir in the cheese. Divide rice mixture evenly among eight peppers and stuff. (Peppers can be stuffed one day ahead and kept covered in the refrigerator.) If grilling, spray the preheated grill grates with cooking spray, place the stuffed peppers on the grill, and close the lid. Turn the peppers every five to six minutes, and cook until they are well-charred on each side. The peppers are finished once the filling is hot and the flesh is soft, about 30 minutes. Alternatively, the peppers can bake in the oven on a greased baking sheet until the cheese is melted and the peppers are heated through, about 30 minutes. Place under the broiler for the last five minutes of cooking, turning once halfway through, to achieve a similar charring that you would get from the grill.
Photograph by Christopher Shane