Steam or boil carrots until extra soft. Drain well. While carrots are warm, add sugar, baking powder and vanilla. Whip with mixer until smooth. Add flour and mix well. Whip eggs and add to flour mixture, blend well. Add softened butter to mixture and blend well. Pour mixture into baking dish about half full as the souffle will rise. Bake in 350 degree oven about 1 hour or until top is a light golden brown. Sprinkle lightly with powdered sugar over top before serving.
Serves 10.