Process all the ingredients for the dough except for the flour with a spatula in a bowl over a low heat, because you have to heat up the dough first. Stirring constantly until the soda stops foaming, you create a thick mass, then set aside and add flour. Knead a smooth dough.
Divide the dough into 2 parts and make sheets of the same size. Roll it while still warm, because it will crack when cold.
Using a rolling pin, carefully transfer the dough onto the baking sheet (have the baking sheet upside down, so that it can be separated more easily after baking). You can cut the dough on the baking sheet so that you don't have any extra parts.
Bake each part of the dough at a temperature of 355 °F / 180 °C for about 5-8 minutes. Carefully remove the baked dough onto a damp cloth and let it cool.
Let's prepare the cream. Cook granulated and vanilla sugar together with milk and flour just like you cook a pudding. When the mass cools down slightly, add it to the mixed butter with powdered sugar and mix well with a mixer until a smooth cream is created.Divide it into 3 parts.
Spread the cream on the baked sheets and layer them. I cut the baked and cooled sheets in half.
Melt the chocolate over steam, add the oil and let it cool slightly. Once it has cooled slightly, spread the chocolate on the top sheet of dough and let it harden. Let the cake layered in this way rest and after a few hours as it will harden nicely, it can be cut without any issues.
