In a bowl, mix: 200g of sugar, vanilla sugar, flour and chopped nuts.
In another bowl, mix the egg whites with 55 g of sugar for 10-12 minutes until we obtain a dense meringue.
Add the meringue over the solid mixture, mix with a spatula in circular motions from bottom to top.
Pour half of the mixture into a 21 cm diameter round ring, lined with baking paper.
Remove the ring and pour in the remaining half of the mixture, thus forming 2 tops.
Place in the preheated oven at 150 °C for 90 minutes.
Remove from the oven and leave at room temperature for 24 hours.
For the Cream: in a saucepan, add the egg yolks and water, mix with a whisk for 2 minutes.
Add the condensed milk and vanilla essence, mix and place on the stove, stirring constantly over low heat until it thickens.
* check the cream: with a spatula or spoon, dip the spoon into the cream, take it out, draw a line with your finger - the edges should remain clean for a while)
Transfer the cream to a bowl, cover with plastic wrap until it touches the cream, and let it cool completely.
Mix the butter at room temperature until it becomes a fluffy cream.
Gradually add a tablespoon of cream while continuing to mix.
Divide the cream into 2 parts, add the cocoa powder to one of them, continue mixing until the ingredients are incorporated.
Cut the edges of the tops with a diameter of 20 cm.
Grind the remaining scraps of the edges.
On a plate, add 1 cake layer, add the white cream and the 2nd cake layer with the smooth surface facing up.
Spread the sides and surface with cocoa cream, decorate the edges with the chopped crumbs.
Place the cake in the refrigerator for 12 hours and then serve.
