Preheat oven to 350. Mix chili, onions and pimento. Mix flour and baking powder. In 10" ovenproof skillet, melt butter, oiling the sides. Beat egg whites wiht salt until stiff. Fold yolks, then flour, into the whites. Spoon in chili, fold until slightly mixed. Pour mixture into hot skillet and place in oven immediately. Bake 20 min.(until center springs back when touched). Sprinkle with cheese, cut into wedges, and serve hot. Serves 6.