Crispy chocolate napoleon cake

The calculation in the recipe is for a 22cm (8.66 inch) cake.

• Pour the flour with cocoa into a mixer bowl, and combine.
• Add the softened butter (cut into cubes) to the flour. Make chocolate crumbs using a mixer (or by hand).
• In a bowl, combine the water, egg, vinegar and salt.
• Turn on the mixer at a low speed (or do it in a bowl or on the table with your hands), and add the liquid mass to the chocolate crumbs in parts. Knead a soft, tender, slightly sticky dough.
• Put the dough on a plate sprinkled with flour, cover with film, and refrigerate for 1-2 hours until cool.
• You better roll out the dough on floured parchment, between 2 sheets of parchment. Then carefully remove the top parchment, cut out a circle of the desired diameter (don't remove the edges, bake with them, they will go to crumbs). Pierce the crust with a fork. Immediately after rolling out and cutting out the circle, do not bake! Let it lie on the table for a couple of minutes.
• Bake the cake layers at 392F (200C) for 10 minutes.

• Bring the milk and sugar to a boil.
• Mix the eggs with flour. Pour a little hot milk into a bowl with eggs, and mix.
• Pour the whole mixture into milk, stirring constantly; bring to a boil, and cool at room temperature.
• Whip the softened butter with condensed milk, add the custard in parts, and whip everything together.

• Assemble the cake in a ring, lining the sides with acetate or cling film.
• Alternate the cake layers and the cream. Place the assembled cake in the fridge overnight.
• Remove the ring and film, sprinkle the top and the sides of the cake with crumbs (make crumbs from scraps, chopping them with your hands).