Butterfly effect cake (No. 2)

My daughter did NOT understand why she couldn't eat the butterfly cake that I brought to work (see butterfly effect cake (No. 1), so I made her this one:

The cake was half a portion of Lemon Moon Cake. Recipe for a full Lemon Moon:
Whip 250 gram of softened butter with 250 grams of icing sugar. Stir in 250 grams of egg (approx. 5 eggs) a little at a time (don't whip/beat the eggs in!). Add 250 grams of flour and 10 gram of baking powder and add grated zests of 2 lemons.

Bake in a well greased tray for approx. 1 hour at 200 degrees.

Make a syrup of the lemon juice (half juice, half sugar - boil to reduce liquid) and pour over cake went it comes out of the oven.

Cover the cake in royal icing (egg white, icing sugar and a little bit of softened unsalted butter - to make sure that the icing remains soft, and the cake may be cut without splintering).