Beat the warm fat, sugar, salt, lemon and orange peel until creamy with the whisk of the hand mixer. Stir in the eggs one after the other. Mix flour, starch and baking powder and stir into the dough alternately with the milk. Grease the oven pan (32x38 cm) and sprinkle with breadcrumbs. Fill in the dough and smooth it down. Bake in the preheated oven (electric: 175 °C/ gas: level 2) for 25-30 minutes. Leave to cool on a grill.
Mix icing sugar with 6-7 tablespoons of orange juice and 6-7 tablespoons of lemon juice until smooth. Remove 4 tablespoons of the icing and colour with food colouring. Pour light icing on the cake and spread. Pour yellow icing into a freezer bag. Cut off one corner and spray the icing onto the cake. Allow to set. Cut the cake into about 24 pieces and serve
waiting time approx. 2 hours