Mix the sugar and egg yolks together well. Add the carrots, hazelnuts, cornstarch and baking powder and slowly stir everything together. Now stir in the egg whites and the water. Grease a loaf pan well with margarine and dust with flour. Now fill in the dough mass. The cake must bake in the preheated oven for 60 minutes at 180 ° C. After baking, leave to cool on a wire rack and dust with powdered sugar. Decorate with marzipan or icing carrots as you wish.