We start with the base layers. Beat the Egg white and Sugar to a stiff snow.
Carefully fold in the Almond flour, pinch of Salt and the Vanilla Sugar. It should stay airy!
Grease the cake form well and add in the egg white Almond flour mixture ½ an inch high. We need 4 base layers! Bake each layer separately at 180 C. for about 10 mins.
Continue with the cream filling. Keep a pot with ⅔ of the above mentioned milk and sugar on the fire and mix ⅓ of the milk with the custard powder. Once the ⅔ amount of milk is hot, add in the ⅓ custard milk mix and mix well with a whisk. Keep on whisking on medium heat till it thickens well. Take form the heat and keep to cool.
In a bowl, beat the butter fluffy and add the Rum. slowly pour in the cooled custard and mix it well. Keep the finished cream mixture for some more time to cool in the fridge.
To assemble the Torte, place the first base layer on a baking sheet and add a ½ inch thick layer of cream on top equally.
Carefully place an other base layer on top of the custard, following a layer of cream.
Again the same procedure, add an other base layer and cream on top.
At last, place the top cover layer.
In a bowl, combine the Icing sugar and Lemon and mix it smooth for the Icing. Take out 3 Tbs of Icing sugar and mix it separately with the cocoa powder. Keep aside.
Take the remaining custard cream and, seal the cake borders with it.
Now pour the white Icing sugar on top of the cake layer cover and equally spread the icing before it gets hard.
Pour the dark icing sugar into a icing bag and pipe the content from the center to the outer parts in a spiral form. Take a toothpick to hand and pass from the center out 8 lines and another 8 lines from the outer to the center, to create the classic Esterhazy design as shown.
Add the Almond slices to garnish at the Torte border, where you had added the extra custard before.