Peel carrots. Clean the zucchini. Wash both and grate them coarsely. Separate the eggs. Beat the egg whites and 3 tablespoons of water with the whisk of the hand mixer until stiff. Let sugar trickle in.
Add the egg yolks and stir in. Mix nuts, breadcrumbs and baking powder and carefully fold into the egg mixture. Squeeze the grated carrots and zucchini well and fold into the dough. Fill the dough onto a greased baking tray (28 x 23 cm) or into a springform pan (26 cm Ø) and smooth it down.
Bake in the preheated oven (electric oven: 200 °C/ gas: level 3) for about 15 minutes. Let them cool down. In the meantime, mix icing sugar and lemon juice and spread on the cooled cake.
Allow to dry. Cut cake into pieces and arrange on a plate. Serve decorated with marzipan carrots and lemon balm. Makes about 9 pieces.