Cake Kiev ~ Киевский Торт

I have been looking forward to making this cake for a long time. So happy that this day is finally here!
Cake Kiev is a very popular cake in Ukraine and all over Russia and Belarus. It's airy structure with small bites of walnuts is a perfect cake to any holiday dinner.
I will cut it at our New Year celebration and will post photos on my Instagram page.
  / lulis.homestead  
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Most cakes require more sugar and butter, however, I have decided to decrease the amount. The custard-butter cream is much softer then the traditional butter cream, yet still holds well in cool temperatures.
Here is my recipe:
Batter-
12 egg whites
2.5 cups sugar
1/2 cups white flour
4 cups walnuts
Bake at 300F for 2 hours

Simple syrup~
1/2 cup water
1/4 cup sugar
1 Tbs rum (or may omit)

Cream~
12 egg yolks
400 ml (1 3/4 cup) milk
1 cup sugar
1 stick soft unsalted butter
(1/2 cup of cream + 4 tsp cacao powder + 1 stick butter) for decor
1/2 cup melted semi-sweet chocolate chips for decor

1 cup walnuts and left over crumble for decor