For each type of dough, sift the flour with salt into a mound, grate cold butter into it and rub together into crumbs with your hands.

Pour in warm water mixed with vodka and knead the dough. Shape into a log, cut into 4 pieces, form into balls and chill for a couple of hours. Do the same with the chocolate dough.

Roll out each ball very thinly on parchment to fit a 16x16 cm square tin. Save the trimmings on a tray for crumbs, and prick each layer with a fork.

Bake the layers at 200-220°C for 7-10 minutes each. Let cool. You should end up with 4 chocolate layers and 4 classic layers.

For the cream, pour the milk into a saucepan. In a bowl, mix the sugar, egg, flour and vanillin until smooth, pour in a little warm milk, stir, then return this mixture to the milk in a thin stream.

Cook the cream over low heat, stirring constantly, until thickened and bubbling. Transfer to another container, add the butter, stir, cover with plastic wrap pressed directly onto the surface and let cool.

Generously coat the layers with cream, alternating colors and without pressing down. Coat the sides and top with crumbs, assemble the cake in the tin, wrap in foil and leave overnight to soak. Decorate as desired.