Separate the egg whites from the yolks. Rub the yolks with the sugar and water, then gradually add the flour, nuts and baking powder quenched with vinegar and mix until smooth. In the previously obtained composition, add the beaten egg whites and mix lightly from top to bottom until the foam is incorporated, then pour it into a tray lined with baking paper.
Place in the preheated oven at 180 ° C for 25 minutes. After it is ready, take it out of the oven and let it cool.
Cream: Put the milk on low heat together with the sugar and the walnut kernel, leave it for about 5 minutes, during which time we stir so that it does not stick to the bottom of the bowl, then pull it aside and let it cool for a few minutes. After this time mix with soft butter at room temperature and vanilla essence.
Grease the top with cream. We thin the chocolate cream (4 lg) in a kettle with a little milk and pour it over the cream.
Put the cake in the fridge for 30 minutes and then cut it.