Mix the flour with the softened butter and sugar, then brake with your hands until to obtain a smooth and compact dough.
Divide the dough in half; in the first half add the vanilla, in the other half add the cocoa.
Put the doughs in the fridge for 30 minutes; past this time, stretch the two cakes separately and then superimpose on each other.
Roll the dough on itself and cut into large slices (each slice better is large about half a centimeter). Place the biscuits on a baking sheet and place for about 10-15 minutes in a preheated oven at 180 degrees.