For 1 rectangular cake tray measuring 25x20cm – Prep: 1 hour 15 mins
Grease a 25 x 20cm cake tin and line the base with baking paper.
Separate 4 eggs, putting the whites into a large, and the yolks into a small bowl.
Add a pinch of salt to the egg whites and beat until stiff.
In a large bowl, beat the butter, sugar and vanilla sugar. Add the 4 egg yolks and beat, then add the remaining two whole eggs and beat again. Add the rum and beat some more.
In a separate bowl, mix the flour, cornstarch and baking powder. Gradually add the flour mix to the butter mix, beating between additions.
Fold in the stiff egg whites with a spatula until you get an even, aerated batter.
Preheat the oven grill to high.
Spread a thin, even layer of batter onto the base of the cake tin and grill just below the oven grill for about 3 minutes until the top has browned.
Meanwhile, put 1½ tbsp sugar, 75ml water and 1½ tbsp rum into a small saucepan and heat until all the sugar has dissolved.
Heat up the apricot jam in a separate saucepan so it becomes runny.
Take the cake tin out of the oven and brush the surface with some apricot jam, then add another thin, even layer of batter. Grill for another 3 minutes until it has set.
Once the second layer is baked, brush some of the rum syrup over the cake.
Spread another layer of batter on top of the cake, pop under the grill for 3 minutes, then brush the grilled surface with apricot jam. Repeat this process until all the dough is used up – alternating between apricot jam and syrup layers (you will get about 10 layers).
Once you get to the last layer, heat the oven to 180°C fan. Bake the cake for 10 minutes to ensure the cake is fully baked.
Leave the cake to cool in its tin for 15 minutes. Turn out onto a wire rack and leave to cool completely.
Once the cake is cool, prepare the icing by mixing all the ingredients together in a small bowl. Spread over the top of the cake and leave to set for a few hours.
Once the icing has set, cut the cake into thin slices and serve.
This cake keeps wrapped in foil for 4 days.