Peel and finely grate the carrots. Separate eggs. Mix egg yolk and sugar until creamy. Stir in cinnamon, lemon peel and juice. Mix nuts, flour and baking powder and add to the egg mixture with the grated carrots and chocolate flakes.
Beat egg whites and salt until very stiff and fold into the dough. Fill the dough into a greased springform pan with breadcrumbs and a tube bottom insert (26 cm Ø) and smooth it down. Bake in the preheated oven (electric oven: 200 °C/ gas: level 3) for approx. 50 minutes.
Remove from the mould and let it cool down on a cake rack. Lightly roast hazelnut slices in a pan without fat. For the icing, stir icing sugar, egg white and baking flavouring until smooth. Cover the cake with it.
Sprinkle with hazelnut slices and chocolate flakes. Let the icing dry. Makes about 16 pieces.