In a large pot of boiling water, cook the carrots until very tender. Drain, and transfer to a large mixing bowl.
While carrots are warm, use an electric mixer to beat with sugar, baking powder, and vanilla extract until smooth. Mix in the flour, eggs, and margarine. Transfer to a 2 quart baking dish.
Bake 1 hour in the preheated oven, or until top is golden brown. Sprinkle lightly with confectioners' sugar before serving.
