In two bowls, separate all 10 eggs. Whisk egg whites on high until soft white foamy peaks start to form. This takes about 5-7 minutes.
Add the softened butter, white sugar, and vanilla extract to the egg yolk bowl and beat for 5 minutes until a creamy mixture is made. Add flour and cornstarch then blend until evenly mixed.
Spoon in large dollops of whipped egg whites into batter and fold in until you can't see any egg whites. Keep doing until all egg whites are gone.
Grease a 8 inch spring form pan including parchment paper and turn on oven broiler to high.
Pour 1/4 cup of cake batter on to the grease spring form pan. Twirl the pan carefully around to evenly distribute cake batter. Put under broiler and cook until a light color is obtained. About 1 minute. Be sure to rotate the pan 180 °F halfway through in order to get an even browning.
Pour the next layer of batter on top of first layer and distribute evenly. Broil second layer at a darker golden brown color. About 2-3 minutes. Keep alternating between light and dark cake layers until all batter is gone.
Once all the layers are broiled, leave cake to cool in tin for 5 minutes then remove and set on wire rack and put into the refrigerator to cool completely.
Frostings
Heat up apricot jam in a small bowl. Stir and push through sieve. Brush jam onto top and sides of the cake.
Melt butter along with corn syrup, rum, and vanilla in a small pan. Bring to a slow boil then remove from heat and add all chocolate.
Let chocolate cool for 5 minutes and then pour onto cake slowly to coat the entire layered cake. Place glaze cake back into the refrigerator for glaze to set.
Whip up the powdered sugar and milk in another bowl until completely smooth. Drizzle white sugar icing over glazed cake.