Put 1 2/3 cups (400 g) of sugar to caramelize until brown in a suitable pot. While stirring nonstop, pour in the boiling water. Stir until the caramel is completely dissolved.
In a separate container, beat the butter with the remaining 1/3 cup (75 g) sugar to a fluffy cream. Add the eggs 1 by 1. Beat well. To the resulting cream, slowly add the flour and then - the milky caramel mixture.
Knead a smooth dough (I had a little sugar syrup left over), put it for 1 hour in the fridge.
Divide the dough into 8 equal-sized parts or balls. Roll out each ball onto baking paper in a thin sheet 8 3/4″ (22 cm) in diameter. Pierce the rolled out sheets with a fork. Bake the 8 layers in a preheated 356°F (180 °C) oven.
To prepare the cream, put the milk in a pot to boil. In a separate container, beat the sugar and eggs to a creamy mixture. To it, add the vanilla and starch and stir well. Once the milk starts to boil, pour in the beaten egg mixture in a thin trickle, while stirring with a whisk nonstop.
Continue stirring until the cream thickens. To the almost ready cream, add the crumbled dark chocolate. Stir well until it dissolves well and becomes a smooth cream. Leave the cream to cool and then add the final ingredient - the softened butter. Stir once again until fully homogenized.
Assemble the cake by first placing a layer, smearing it with cream, placing another layer and so on until you've placed the final one. Finish it off by covering everything with cream at the end.
And for the final touch you can cover the cake with a chocolate ganache made from 5.5 oz (150 g) chocolate and 3 1/3 tbsp (50 g) cream.
It's a cake made for the holidays and the decoration should also be suitably festive (although I wasn't feeling creative at the time).
And one more tip: always use quality ingredients. I made the mistake of buying plain dark chocolate and the taste wasn't exactly as I wanted it. Otherwise, the cake is unique to the taste and deserves all the hassle and to be made with quality products.